WASHINGTON – President Clinton said yesterday that his wife would be an excellent choice as the first female American president, and he pledged to do all he could to help her win if she chooses to run in 2008.

The former president’s comments are likely to reinforce speculation that New York’s junior senator is a likely contender for the 2008 race for the White House.

One of Senator Clinton’s potential rivals for the Democratic presidential nomination went as far as to suggest yesterday that the party’s nomination is hers for the asking.

“I think she is likely to be the nominee,” Senator Biden of Delaware said.

“She would be the toughest person. And I think Hillary Clinton is able to be elected president of the United States,” Mr. Biden said on NBC’s “Meet the Press.”

Mrs. Clinton is seeking re-election to the Senate next year and has been mum on her presidential ambitions. A Gallup opinion poll last week found Mrs. Clinton’s popularity with female voters has the potential to draw votes from Republican and independent women.

Mr. Clinton told Japan’s TV Asahi yesterday that does not know whether Mrs. Clinton wants to seek the office he occupied for eight years.

“I don’t know if she’ll run or not,” he told the network, but he said, “She would make an excellent president, and I would always try to help her,” according to a report of his remarks from the Associated Press.

Mr. Clinton said his wife would make “a very, very good president.” When asked which spouse was more politically talented, he said, “I was in it more, so for a long time I was better. But I think now she’s at least as good as I was,” the AP reported.

The senator’s recent speeches and appearances have been scrutinized for evidence of presidential ambitions. When she recently called on people on both sides of the abortion debate to seek “common ground,” the senator was seen as shifting to the political center, though she said she was expressing long-held views and not altering her stance that women should have the option of choosing abortion.

The former first lady will be the “most difficult obstacle for anyone” seeking the nomination, Mr. Biden said yesterday.

Mr. Biden, who made a failed bid for the presidency in 1988, said he would decide by the end of this year whether to mount another campaign.

Other potential Democratic contenders include Senators Kerry of Massachusetts, Edwards of South Carolina, Bayh of Indiana, and Feingold of Wisconsin; and Governors Vilsack of Iowa, Richardson of New Mexico, and Warner of Virginia.

Another frequently mentioned potential presidential hopeful, Governor Schwarzenegger of California, yesterday cast doubt on his presidential ambitions.

“I have never thought about running for president, and this is not my vision,” the Republican governor said on ABC News’s “This Week with George Stephanopoulos.”

The Austrian-born former actor and bodybuilder said he did not enter politics with an eye on the White House.

“My goal was not to run for president. My goal was to run for governor, to become governor, and then to reform the system and to do the kind of things that no one wanted to do because it’s too dangerous in politics to do,” he said.

Mr. Schwarzenegger said comments he made in 1977, stating that he planned to run for president, were a joke. A Schwarzenegger candidacy would face numerous obstacles, including the distance between his views on abortion, gay rights, and the death penalty and those of the Republican Party’s more conservative and religious base.

Mr. Schwarzenegger, a Catholic, said he was not concerned about reconciling his politics with his religious beliefs.

“As a matter of fact, religion should have no effect on politics,” he said.

The overriding obstacle facing a Schwarzenegger candidacy is the need for a constitutional amendment to allow foreign-born American citizens to serve as president.

Supporters of his candidacy have sparked a movement for such an amendment – which would require approval of Congress and state legislatures. But two influential lawmakers rebuffed the idea yesterday.

Senator Santorum, a Republican of Pennsylvania, said he “probably wouldn’t” vote for such an amendment.

“I don’t see a great need to change that area of the Constitution,” he said on “Meet the Press.”

Mr. Santorum is also mentioned as a potential 2008 candidate. Yesterday he said he has “no intention” of running for president, but when pressed he would not rule it out.

Mr. Biden likewise said he did not favor the amendment.

“I’m incredibly reluctant to amend the Constitution for any purpose,” Mr. Biden said.

Mr. Schwarzenegger said yesterday that an amendment would be “very difficult” to achieve, and “something you can’t really rush,” but he called for an “open debate” on the subject.

Other frequently mentioned candidates for the Republican presidential candidacy include the majority leader in the Senate, Bill Frist of Tennessee, Senator Graham of South Carolina, Mayor Giuliani, and several governors, including George Pataki and Mitt Romney of Massachusetts.