WASHINGTON — The top presidential candidates and their big-name supporters campaigned from coast to coast yesterday, but one contender seemed atop everyone's mind: Hillary Rodham Clinton.

Republicans John McCain and Mitt Romney contrasted themselves, and each other, with Clinton as though she were the nominee. Her Democratic rival, Barack Obama, played along to a degree, saying Clinton is so polarizing that he is their party's better bet.

Rather than diverting the attention, Clinton embraced it.

"I've been taking the incoming fire from Republicans for about 16 years now, and I'm still here, because I have been vetted, I have been tested," she said in a TV interview before campaigning in Missouri and Minneapolis.

"There's unlikely to be any new surprises," Clinton added, implying the same cannot be said of Obama, who has been in Congress three years.

Her confidence notwithstanding, polls showed Obama narrowing the lead that Clinton has enjoyed among Democrats nationwide, even as McCain appeared to be pulling away from Romney.

With 24 states holding presidential contests tomorrow, yesterday was an intense day of campaigning and advertising, making it all the more remarkable that one figure managed to dominate so much of the talk.

The New York senator and former first lady is the Democrat conservatives most love to hate, and McCain and Romney campaigned against her as if in a proxy battle against one another.

"If we want a party that is indistinguishable from Hillary Clinton on an issue like illegal immigration," Romney said, "we're going to have John McCain as a nominee. That's the wrong way to go."

McCain, campaigning in Fairfield, Conn., said he has never sought special projects for his state, and added: "In her short time in the United States Senate, the senator from New York, Sen. Clinton, got $500 million worth of pork barrel projects. My friends, that kind of thing is going to stop."

The Clinton fascination is trickier for Obama. He wants to capitalize on Republicans' opposition to her without agreeing that she is the inevitable nominee.

Speaking on CBS' "Face the Nation" before campaigning in Delaware, the Illinois senator said the problem is "not all of Sen. Clinton's making, but I don't think there's any doubt that the Republicans consider her a polarizing figure."

OBAMA RALLIES

Obama drew a crowd of 20,000 in downtown Wilmington, but his campaign attracted attention in other places, too. At a Los Angeles event, his stand-ins were his wife, Michelle; TV star Oprah Winfrey; and Caroline Kennedy, daughter of President Kennedy.

They were joined by Maria Shriver, the wife of California Gov. Arnold Schwarzenegger, who followed in the steps of Caroline and their uncle, Sen. Edward M. Kennedy, in endorsing Obama.

"I thought, if Barack Obama was a state, he'd be California," she said to a crowd of 9,000 inside UCLA's Pauley Pavilion. "Diverse, open, smart, independent, bucks tradition. Innovative. Inspirational. Dreamer. Leader."

As usual, another prominent Clinton — the candidate's husband and former president — was in the thick of things.

Bill Clinton visited four churches in mostly black sections of Los Angeles. The former president never mentioned Obama by name when he spoke for about 20 minutes at the City of Refuge church in Gardena. But he struck a conciliatory tone in describing this year's Democratic contest as "an embarrassment of riches."

Campaigning in a western suburb of Chicago, Romney took a swipe at Obama, again as a means of nicking McCain.

"Yesterday Barack Obama said there's not a dime's worth of difference between he and Sen. McCain on illegal immigration," Romney told a crowd at the College of DuPage. "I'm afraid it's going to be real hard to win the White House if there's not much difference between our nominee and theirs, and that's why I'm going to make sure that we stand for Republican ideals and win the White House on that platform."

McCain largely shrugged off such jibes, although he said he is "much more conservative" than Romney.

A third GOP candidate, former Arkansas Gov. Mike Huckabee, struggled for attention and rejected suggestions that he step aside.

"I'll stay in until someone has 1,191 delegates," he said in a telephone interview with The Associated Press from Kennesaw, Ga., referring to the number of convention delegates needed to secure the party nomination.

HEALTHCARE PLANS

In a day dominated by familiar stump speeches, Hillary Clinton made news by saying she might allow workers' wages to be garnisheed if they refuse to buy health insurance.

She has criticized Obama for pushing a health plan that she says would not require universal coverage.

She said such measures would apply only to workers who can afford health coverage but refuse to buy it, which puts undue pressure on hospitals and emergency rooms.

Under her plan, she said, healthcare "will be affordable for everyone" because she would limit premium payments "to a low percent of your income."

Obama has said he would require parents to buy health insurance for children, and possibly fine them if they refused. But he would not insist that all adults buy insurance.