DENVER (AP) — Republicans on Tuesday invoked Hillary Rodham Clinton’s past criticism that Barack Obama wasn’t ready to lead as Democrats faced two days at their national convention to be dominated by the old Clinton regime.

Clinton, Obama’s former rival for the nomination, was expected to urge her disappointed supporters to line up in unity behind Obama in a prime-time speech to the Democratic National Convention. Her husband, former President Clinton, speaks to the convention on Wednesday night.

Some Democratic activists, meanwhile, voiced concern that the convention, which began on Monday, had yet to produce a sustained or effective attack against Republican presidential candidate John McCain.

In particular, they cited comments by former Virginia Gov. Mark Warner, who also was to address the convention Tuesday night, suggesting that his speech would not be a red-meat attack on McCain but an appeal for bipartisanship.

“There may be parts of the speech that aren’t going to get a lot of applause, but I’ve got to say what I believe will get out country back on the right path,” Warner told reporters on Monday.

Democratic strategist Paul Begala took issue with Warner’s comments, suggesting that more partisanship, not less, is needed at the party convention.

“This isn’t the Richmond Chamber of Commerce,” Begala said Tuesday.

On Monday, James Carville, who managed Bill Clinton’s successful 1992 campaign, told CNN: “If this party has a message, it’s done a hell of a job hiding it tonight, I promise you that.”

The day Clinton was to address the convention, McCain’s latest TV ad played off her primary campaign spot featuring sleeping children and a 3 a.m. phone call portending a crisis. In the new ad Clinton is shown saying: “I know Sen. McCain has a lifetime of experience that he will bring to the White House. And, Sen. Obama has a speech he gave in 2002.”

A narrator adds: “Hillary’s right. John McCain for president.”

Clinton has already denounced such tactics. “I’m Hillary Clinton and I do not approve that message,” she told members of the New York delegation on Monday.

Meanwhile, McCain is expected to name his running mate in the coming days.

A top surrogate and prospective No. 2, former Massachusetts Gov. Mitt Romney was to be in Denver on Tuesday to assail Democrats on behalf of McCain. It amounted to a final audition of sorts as McCain seeks a strong running mate who can play the attack-dog role against Obama and running mate Joe Biden. Another Republican said to be a serious vice presidential contender, Minnesota Gov. Tim Pawlenty, was scheduled to be in Denver doing the same on Thursday.

Clinton once seemed to have the nomination in her grasp and now is being called on to defend and support the person who wrested it from her. She is effectively playing middlewoman Tuesday night — passing a torch from her husband, the 42nd president, to Obama, who wants to succeed him as the next Democratic president.

But not without some Clinton-style political dealmaking and drama.

The Clinton and Obama camps agreed to limit Wednesday’s divisive nominating process for president, allowing some states to cast votes for both Obama and Clinton before ending the roll call in an acclamation for the Illinois senator.

In one scenario, Clinton herself would cut off the voting and urge the unanimous nomination of Obama, according to Democratic officials involved in the negotiations. They discussed the deal on condition of anonymity while final details were being worked out.

But some Clinton delegates said they were not interested in a compromise, raising the prospect of divisive floor demonstrations.

“I don’t care what she says,” said Mary Boergers, a Maryland delegate who wants to cast a vote for Clinton.

“There is no doubt in anyone’s mind that this is Barack Obama’s convention,” Clinton told reporters. And yet, she said, some of her delegates “feel an obligation to the people who sent them here” and would vote for her.

As part of the deal, Obama and Clinton activists teamed up and circulated three petitions on the convention floor Monday night — supporting Clinton, Obama and his running mate, Joe Biden. Each needed 300 signatures.

Clinton said she wouldn’t tell her backers how to vote, but she told them she would cast her own vote for Obama.

As well as Clinton’s speech, the lineup for the second day of the convention features 11 governors and prominent House and Senate leaders. The convention’s keynote address will be given by Warner, a former Clinton supporter.

The Clintons will dominate the next two days of the convention, just as they have dominated Democratic politics for the past 16 years

Tuesday morning, Bill Clinton was participating in a panel at the Club of Madrid NDI International Affairs Forum “to discuss ways in which his foundation is addressing some of the world’s most pressing problems,” said his spokesman, Matt McKenna.

The former president planned few other public outings, and no news media appearances.

“President Clinton understands this is Sen. Obama’s convention and he is here to do all he can to make Sen. Obama our next president,” McKenna said in an e-mail message.

Asked whether the Clintons’ star power could eclipse Obama during his moment in the sun, House Speaker Nancy Pelosi said, “Absolutely, positively not.”

“We’re talking about the nominee for the president of the United States,” she said.