TAMPA, Fla. - Barack Obama criticized John McCain yesterday where it could hurt most - over the Arizona senator's reputation as a champion of ethics. Hillary Rodham Clinton raised the possibility she might carry her fight to the Democratic convention floor.

With more superdelegate endorsements after Tuesday's Kentucky and Oregon primaries, Obama was just 64 delegates short of the 2,026 currently needed to clinch his party's nomination.

The Illinois senator detoured from the three remaining primary sites - Puerto Rico, Montana and South Dakota - to campaign in Florida, a crucial state in the Nov. 4 election. He also kept his focus on McCain, the Republicans' presumptive nominee.

Obama said McCain had lost faith with his own good-government principles. Ten years ago, Obama said, McCain proposed barring registered lobbyists from working for candidates' campaigns.

"John McCain then would be pretty disappointed in John McCain now, because he hired some of the biggest lobbyists in Washington to run his campaign," Obama told a crowd of 15,000 at a Tampa arena.

McCain recently instituted a no-lobbyist policy on his campaign, forcing out some top aides.

"And when he was called on it, his top lobbyist actually had the nerve to say the American people won't care about this," Obama said.

With McCain fund-raising in California, campaign spokesman Tucker Bounds responded: "Despite his own rhetoric, Senator Obama still refuses to disclose the list of lobbyists advising his campaign."

"We challenge Senator Obama to meet our standard" for keeping lobbyists out of the campaign organization, Bounds added.

Clinton, too, was in Florida, pressing to narrow her gap with Obama by having delegates counted from its renegade January primary.

Democratic rule-makers are to meet May 31 to decide whether to count delegates from Florida and Michigan; the states were stripped of their delegates because they held early primaries in violation of party rules. Clinton won both states, but Obama had had his name removed from Michigan's ballot and neither candidate campaigned in those states.

In an interview yesterday with the Associated Press, Clinton said she was willing to take her fight to seat Florida's and Michigan's delegates to the convention if the two states wanted to go that far.

Asked whether she would support the states if they appeal an unfavorable rules committee decision to the convention floor, the New York senator replied: "Yes I will. I will, because I feel very strongly about this."

"I will consult with Floridians and the voters in Michigan because it's really their voices that are being ignored and their votes that are being discounted," she said.

An increasing number of party leaders say the contest needs to be wrapped up shortly after the last primaries June 3 to prepare adequately for the fall election.

Asked whether she envisioned the race extending beyond June 3, Clinton said: "It could. I hope it doesn't."

Clinton pressed the delegate-seating issue at an appearance in Boca Raton in Palm Beach County, a key site in the 2000 battle between George W. Bush and Al Gore over the vote recount that ultimately was decided by the Supreme Court.

Floridians "learned the hard way what happens when your votes aren't counted and the candidate with fewer votes is declared the winner," she told supporters.

On the Republican side yesterday, McCain adviser Mark Salter described as "purely social" the invitations to McCain's Sedona, Ariz., retreat this holiday weekend extended to at least three Republicans some have mentioned as potential running mates: Florida Gov. Charlie Crist, Louisiana Gov. Bobby Jindal, and former Massachusetts Gov. Mitt Romney.

Specter: Pa. GOP Has Work to Do

Sen. Arlen Specter

(R., Pa.) said yesterday that the Pennsylvania Republican Party needs to do more to win back the thousands of voters who switched parties

to participate in the

April 22 Democratic presidential primary.

The five-term senator

said many of the voters were the independents he wants on his side when he is up for reelection in 2010. Specter, 78, has a recurrence of Hodgkin's disease but said he was keeping a full schedule.

He said it worried

him that leading up to the Pennsylvania primary, GOP registrations in the state dropped nearly 2 percent from last fall. Democratic registrations were up nearly 8 percent, to more than four million voters.

Specter said

he thought many people switched just to vote in the Democratic primary and would switch back. But it is "going to take some work" to get some of them back, he said.

He said he wa

s talking to his major contributors about donating money as part of the effort to increase the state's GOP registrations. He said he had also asked the presumptive GOP presidential nominee, John McCain, to help with the effort.

- Associated Press