The plans of presidential candidates are never set in stone, if only because circumstances and the makeup of Congress change after the election.

The uncertainty is even deeper in this election because Democrat Barack Obama and Republican John McCain laid out most of their agenda before the government committed up to $700 billion to address the financial crisis.

Obama acknowledges what is true for both: "The next president will have to scale back his agenda and some of his proposals." Yet neither candidate has spelled out what promises might have to be postponed or changed.

With that caution, here's a look at where McCain and Obama stand on a selection of issues:

ABORTION

McCain: Opposes abortion rights. Has voted for abortion restrictions permissible under Roe v. Wade, and now says he would seek to overturn that guarantee of abortion rights. Would not seek constitutional amendment to ban abortion.

Obama: Favors abortion rights.

AFGHANISTAN

McCain: Favors unspecified boost in U.S. forces.

Obama: Would add about 7,000 troops to the U.S. force of 36,000, bringing the reinforcements from Iraq. Has threatened unilateral attack on high-value terrorist targets in Pakistan as they become exposed, "if Pakistan cannot or will not act" against them.

CAMPAIGN FINANCE

McCain: The co-author of McCain-Feingold campaign finance law is running his general campaign with public money and within its spending limits. He urged Obama to do the same. He applied for federal matching funds for primaries but later turned them down so he could spend more than the limits. The Federal Election Commission belatedly approved his decision to bypass the primary funds, but rejected McCain's claim that he needed no such approval. He raised more than $160 million before having to stop to accept the $84 million in public money for the fall. McCain accepted primary campaign contributions from lobbyists.

Obama: The presidential campaign's fundraising champion has brought in more than $605 million. He is raising private money for his general election, despite his proposal last year to accept public financing and its spending limits if the Republican nominee did, too. He raised a record-shattering $150 million in September. Obama refuses to accept money from federal lobbyists and has instructed the Democratic National Committee to do the same for its joint victory fund, an account that would benefit the nominee. Obama does accept money from state lobbyists and from family members of federal lobbyists.

CUBA

McCain: Ease restrictions on Cuba once U.S. is "confident that the transition to a free and open democracy is being made."

Obama: Ease restrictions on family-related travel and on money Cuban-Americans want to send to their families in Cuba. Open to meeting new Cuban leader Raul Castro without preconditions. Ease trade embargo if Havana "begins opening Cuba to meaningful democratic change."

DEATH PENALTY

McCain: Has supported expansion of the federal death penalty and limits on appeals.

Obama: Supports death penalty for crimes for which the "community is justified in expressing the full measure of its outrage." As Illinois lawmaker, wrote bill mandating videotaping of interrogations and confessions in capital cases and sought other changes in system that had produced wrongful convictions.

EDUCATION

McCain: He is not proposing a federal voucher program that would provide public money for private school tuition, in contrast to his proposed $5 billion voucher plan in 2000. Only proposes expansion of District of Columbia's voucher program. Sees No Child Left Behind law as vehicle for increasing opportunities for parents to choose schools. Proposes more money for community college education.

Obama: An $18 billion plan that would encourage, but not mandate, universal pre-kindergarten. Teacher pay raises tied to, although not based solely on, test scores. An overhaul of No Child Left Behind law to better measure student progress, make more room for subjects such as music and art and be less punitive toward failing schools. A tax credit to pay up to $4,000 of college costs for students who perform 100 hours of community service a year. Obama would pay for part of his plan by ending corporate tax deductions for CEO pay. Has backed away from his proposal to save money by delaying NASA's moon and Mars missions.

ENERGY-GLOBAL WARMING:

McCain: Favors increased offshore drilling and building 45 nuclear power reactors by 2030. Opposes drilling in Alaska's Arctic National Wildlife Refuge. Mandatory reductions of carbon dioxide and other greenhouse gases by 60 percent from 1990 levels by 2050, using a market-based cap-and-trade system that would increase energy costs. Supports $2 billion program to develop carbon capture and other clean coal research and development. $5,000 tax credit for the purchase of zero carbon emission cars; $300 million prize for improved batteries for hybrid vehicles. Broke with President Bush on global warming and led Senate effort to cap greenhouse gas emissions.

Obama: Ten-year, $150 billion fund for biofuels, wind, solar, plug-in hybrids, clean-coal technology and other "climate-friendly" measures. Mandatory reductions of carbon dioxide and other greenhouse gases by 80 percent from 1990 levels by 2050, using a market-based, cap-and-trade system that would increase energy costs. Increase federal fuel economy requirements from 35 mpg to 40 mpg. Now would consider limited expansion of offshore oil and gas drilling. Opposes drilling in Arctic National Wildlife Refuge. Proposes windfall-profits tax on largest oil companies to pay for energy rebate of up to $1,000. Expand federal requirements for ethanol from 36 million gallons to 60 million gallons a year with increase coming from non-corn sources, and require utilities to produce 25 percent of power from renewable energy such as wind, solar and biomass by 2025. $7,000 tax credit for the purchase of advance-technology vehicles; put 1 million plug-in hybrid cars on road by 2015.

FINANCIAL CRISIS

McCain: $300 billion plan for the government to buy bad mortgages and renegotiate them at a reduced price. Proposes a one-year suspension of requirements that people aged 70 1/2 begin cashing in retirement accounts. Lobbied fellow lawmakers to support $700 billion rescue plan. Eliminate taxes on unemployment benefits, guarantee 100 percent of savings for six months, lower the tax rate on retirement funds to 10 percent, on the first $50,000 withdrawn. Cut the tax rate on capital gains by half, to 7.5 percent, for two years.

Obama: Two-year plan offering $3,000 tax credit to businesses for each new job created and enabling people to withdraw up to 15 percent of their retirement money, to a maximum of $10,000, without penalty, except for the usual taxes. Would temporarily extend an expiring tax break that lets small businesses immediately write off investments of up to $250,000, and sweeten small-business loans at a cost of about $5 billion. Estimated cost of proposals: $60 billion. Now favors mandatory 90-day freeze on some foreclosures. Lobbied fellow lawmakers to support $700 billion rescue plan. Extend unemployment benefits, offer tax credit covering 10 percent of annual mortgage-interest payments for "struggling homeowners."

GAY MARRIAGE

McCain: Opposes constitutional amendment to ban it. Says same-sex couples should be allowed to enter into legal agreements for insurance and similar benefits, and states should decide about marriage. Supports the federal Defense of Marriage Act, which denies federal recognition of same-sex marriages and gives states the right to refuse to recognize such marriages.

Obama: Opposes constitutional amendment to ban it. Supports civil unions, says states should decide about marriage. Switched positions in 2004 and now supports repeal of Defense of Marriage Act, which denies federal recognition of same-sex marriages and gives states the right to refuse to recognize such marriages.

GUN CONTROL

McCain: Voted against ban on assault-type weapons but in favor of requiring background checks at gun shows. Voted to shield gun-makers and dealers from civil suits. "I believe the Second Amendment ought to be preserved — which means no gun control."

Obama: Voted to leave gun-makers and dealers open to suit. Also, as Illinois state lawmaker, supported ban on all forms of semiautomatic weapons and tighter state restrictions generally on firearms.

HEALTH CARE

McCain: $2,500 refundable tax credit for individuals, $5,000 for families, to make health insurance more affordable. No mandate for universal coverage. Would no longer shield from income taxes those payments that businesses and their workers make toward employer-sponsored health insurance. Tax Policy Center estimates overall plan's cost at $1.3 trillion over 10 years.

Obama: Mandatory coverage for children, no mandate for adults. Aim for universal coverage by requiring larger employers to share costs of insuring workers and by offering coverage similar to that in plan for federal employees. Proposes spending $50 billion on information technology over five years to reduce health care costs over time. Tax Policy Center estimates overall plan's cost at $1.6 trillion over 10 years.

IMMIGRATION

McCain: Sponsored 2006 bill that would have allowed illegal immigrants to stay in the U.S., work and apply to become legal residents after learning English, paying fines and back taxes and clearing a background check. Now says he would secure the border first. Supports border fence.

Obama: Voted for 2006 bill offering legal status to illegal immigrants subject to conditions, including English proficiency and payment of back taxes and fines. Voted for border fence.

IRAN

McCain: Favors tougher sanctions, opposes direct high-level talks with President Mahmoud Ahmadinejad.

Obama: Initially said he would meet Ahmadinejad without preconditions, now says he's not sure "Ahmadinejad is the right person to meet with right now." But says direct diplomacy with Iranian leaders would give U.S. more credibility to press for tougher international sanctions. Says he would intensify diplomatic pressure on Tehran before Israel feels the need to take unilateral military action against Iranian nuclear facilities.

IRAQ

McCain: Opposes scheduling a troop withdrawal, saying latest strategy is succeeding. Supported decision to go to war, but was early critic of the manner in which administration prosecuted it. Was key backer of the troop increase. Willing to have permanent U.S. peacekeeping forces in Iraq.

Obama: Spoke against war at start, opposed troop increase. Voted against one major military spending bill in May 2007; otherwise voted in favor of money to support the war. Says his plan would complete withdrawal of combat troops in 16 months. Initially had said a timetable for completing withdrawal would be irresponsible without knowing what facts he'd face in office.

SOCIAL SECURITY

McCain: "Nothing's off the table" when it comes to saving Social Security.

Obama: Would raise payroll tax on wealthiest by applying it to portion of income over $250,000. Now, payroll tax is applied to income up to $102,000. Rules out raising the retirement age for benefits.

STEM CELL RESEARCH

McCain: Supports relaxing federal restrictions on financing of embryonic stem cell research.

Obama: Supports relaxing federal restrictions on financing of embryonic stem cell research.

TAXES

McCain: Proposes extending all of President Bush's tax cuts and cutting corporate tax rate to 25 percent. Pledged not to raise taxes, then equivocated, saying nothing can be ruled out in negotiating compromises to keep Social Security solvent. Twice opposed Bush's tax cuts, at first because he said they were tilted to the wealthiest and again because of the unknown costs of Iraq war. Now says those tax cuts, expiring in 2010, should be permanent. Nonpartisan Tax Policy Center estimates tax break of $325 for the middle 20 percent of taxpayers — those making $37,600 to $66,400.

Obama: Raise income taxes on families making over $250,000 and individuals making over $200,000. Raise corporate taxes. $80 billion in tax breaks mainly for poor workers and elderly, including tripling Earned Income Tax Credit for minimum-wage workers and higher credit for larger families. Eliminate tax-filing requirement for older workers making under $50,000. A mortgage-interest credit could be used by lower-income homeowners who do not take the mortgage-interest deduction because they do not itemize their taxes. Nonpartisan Tax Policy Center estimates tax break of $1,118 for the middle 20 percent of taxpayers — those making $37,600 to $66,400.

TRADE

McCain: Free trade advocate.

Obama: Seek to reopen North American Free Trade Agreement to strengthen enforcement of labor and environmental standards. In 2004 Senate campaign, called for "enforcing existing trade agreements," not amending them.