WASHINGTON — Now that she has won on primary night after a monthlong drought, Hillary Rodham Clinton must decide how fiercely to wage a spring offensive against unforgiving odds that could scar Barack Obama in a fall campaign. Clinton claimed victories in Ohio, Texas and Rhode Island that stopped the Obama juggernaut.

On the Republican side, John McCain swept the day's four GOP primaries to clinch the Republican nomination and force Mike Huckabee from the race.

Obama won as expected in the Vermont primary, making certain no Clinton sweep was in the wind.

In her victories, Clinton stemmed the shift of working-class and white voters to the Obama campaign and possibly regained the upper hand on issues of vital concern to Democrats — healthcare, jobs and the pains of globalization.

Winning 11 straight contests had put Obama in commanding position and he was likely to remain the front-runner regardless of the outcomes yesterday.

But Clinton revived herself at least temporarily, much as she did in New Hampshire two months ago after a sharp-edged campaign that forced the Illinois senator on the defensive for the first time in weeks and called into question his ability to protect families in the event of an international crisis.

Clinton gave no indication of wavering in her resolve, asserting last night that she was just getting started.

"The people of Ohio have said it loud and clearly: We're going on, we're going strong and we're going all the way," Clinton said, ticking off a list of her primary victories this season.

Speaking in Texas, Obama said no matter what happened yesterday, "we have nearly the same delegate lead as we had this morning and we are on our way to winning this nomination."

Obama took the lead in Texas caucuses before counting closed for the night — 55 percent to 44 percent, with results in from 40 percent.

Despite her success, Clinton's prospects of overcoming Obama's pledged-delegate lead looked bleak. Obama's victory streak since Feb. 5 Super Tuesday voting had yielded a 113-delegate lead, according to an Associated Press tally, and Clinton stood to barely cut into that margin yesterday.

DELEGATE GAP

To prevail in the end, Clinton needs to dramatically reverse the course of the campaign by winning by big margins in the final dozen widely interspersed contests, steam-rolling in the Pennsylvania primary on April 22. But even that scenario with an unlikely 20-percentage point victory in Pennsylvania yielding a 32-delegate pickup would leave her dozens of delegates behind Obama.

Obama's immediate path looked easier with the next primary of note March 11 in Mississippi, where a 36 percent black populous would lean toward Obama, an African-American, in the competition for 33 delegates. Wyoming's Democratic Party caucus on Saturday is the next contest; just 12 delegates are at stake.

Clinton would need to carry on a gut-punching campaign far into spring, with the last significant contests on May 6 in North Carolina and Indiana, with a total of 187 delegates at stake, and May 20 in Kentucky and Oregon, with 103 delegates at stake.

Nonetheless, Clinton demonstrated resilience in Ohio. Exit polls showed that she captured six in 10 voters with no more than a high-school education in a state that has lost a staggering 236,000 factory jobs this decade.

In her spirited stand, Clinton deployed a memorable television ad featuring a phone ringing in the White House bearing news of an emergency. "It's 3 a.m. and your children are safely asleep. Who do you want answering the phone?"

Obama responded with a ringing-phone ad of his own asserting that Clinton had failed her 3 a.m. moment by supporting the White House decision to invade Iraq. But judging by exit polls in Texas, Clinton won the phone ad competition: By 55-39 percent, Democrats said that Clinton was most qualified to be president.

Clinton faced an expectations-management problem yesterday caused by her husband, the former president, who asserted while exhorting voters that she had to win both Ohio and Texas to have a chance at the nomination. Even so, virtually no winning scenario exists that doesn't include an Obama collapse and a mass movement of super-delegates toward Clinton.

DIMINISHING RETURNS

Yesterday's results fueled the debate of when the Democratic race will reach the point of diminishing returns for the party. The star power and history-making subtext to the Clinton-Obama duel has fueled record turnouts and energy that Democrats said can be marshaled for November.

But party officials also have warned of dangers if the tenor grows harsh, a worry that grew in recent days with Clinton's sharply honed attacks that speak to Obama's inexperience. She succeeded in shining the light on Obama by chiding reporters for what she said was a kid-gloves approach to the Illinois senator, and by trumpeting his connections to a Chicago restaurateur and developer who went on trial in federal court this week on extortion and other charges.

Clinton's defenders observe that Obama would face far worse from Republicans in the fall. Even so, party insiders have worried that a free-swinging Clinton campaigning through Pennsylvania — a full seven weeks away — would lay a foundation for the GOP's general election campaign.

In a year in which Obama's bottom-up politics have been the primary season's most potent force, it seems unlikely that Clinton's call for a top-down super-delegate solution could succeed. Democrats of all stripes seem strongly averse to party heads dictating the nominee; in exit polls yesterday, 60 percent or more of Democrats said that super-delegates should fall in line with the will of the people.

Exit polls also found that Ohio voters who were anxious about their family finances or overall economy said they favored Clinton over Obama.

Clinton also was benefiting from a gender gap among anxious voters in Texas and Ohio, where roughly six in 10 Democratic voters are women. Clinton also was winning decisively among Hispanic voters in Texas, according to network exit polls.

Obama carried white men in both states, and he carried voters under 30 by more than 2-1, the same margin by which Clinton won voters 60 and older. But in Ohio, senior citizens made up nearly a quarter of the Democratic vote, while those under 29 made up just 16 percent, according to the exit polls.

Clinton also enjoyed an edge among voters making less than $50,000 a year, who comprised about half the electorate.

Obama performed best, as he has throughout the campaign, among blacks — winning nine in 10 of their votes — voters under age 30, college graduates and those making more than $100,000 a year.

The Los Angeles Times contributed to this report.