(CBS News) WASHINGTON - After five more primary wins, Mitt Romney said the race for the Republican nomination for president is over and now it's time to defeat President Obama.
And as Romney gets closer to clinching the nomination, a chief rival appears ready to bow to the seemingly inevitable.
Romney declared victory Tuesday night, not just in the states holding primaries but in the GOP race, telling cheering supporters in Manchester, N.H., "Together, we will win on Nov. 6!"
He then took aim at Mr. Obama, saying, "The last few years have been the best that Barack Obama can do, but it's not the best America can do. Tonight is the beginning of the end of the disappointments of the Obama years."
Romney's five-state sweep -- in Connecticut, Rhode Island, Pennsylvania, New York and Delaware -- locked in his standing as the GOP's nominee-in-waiting. But he still needs 298 more delegates for it to be official.
A CBS News/New York Times poll shows Republicans falling in line; 54 percent say they want Romney to be the nominee.
Even a former Romney rival offered some support Tuesday night.
"He's the person that's going to go up against Obama, it's pretty clear, and we need to win this race," Rick Santorum said on CNN's "Piers Morgan Tonight."
Asked if that's an endorsement, Santorum responded, "If that's what you want to call it, you can call it whatever you want."
That's as close as he got to endorsing Romney.
And Newt Gingrich appears close to dropping out and lining up behind the front-runner, saying before the results were in, "We are going to think carefully how we can be the most helpful to this country. ... Governor Romney is going to have a very good night. ... If he does end up as the nominee, I think every conservative in this country has to be committed to defeating Barack Obama.
"And," he said to cheers, "let's be very clear about that."
Romney is still struggling to get support from the conservative base of the Republican Party, but GOP analysts say that, as Election Day approaches and those conservative GOP voters think about the prospect of a second Obama term, that will be plenty enough to get them fired up.
To see Chip Reid's report, click on the video in the player above.