On this day in 1968 Richard Nixon announces his candidacy for president. Also on this day in 2003 the space shuttle Columbia broke up upon re-entry. On to today's top stories:

"Head to Head, Clinton, Obama Shelve Rancor" (Dan Balz and Anne Kornblut, Washington Post) Even if it wasn't the smackdown many had hoped for, the Clinton-Obama one-on-one was still a spirited debate, as each sought to clearly emphasize their own strengths and differences and point out the other's weaknesses. Between them, a general target was the Republicans and both got off their best lines of the night attacking the other side. But did Obama do enough to overcome Hillary's Feb. 5 lead in the polls? Didn't look like it.

"As McCain Wins, Critics on Right Look Again" (David Kirkpatrick, New York Times) Faced with the possibility that John McCain might be the Republican standard bearer, former conservative critics are trying to find the silver lining his in his candidacy.

"Romney's Comeback Plan Champions His Conservatism" (Elizabeth Holmes, Wall Street Journal) We seem to have come full-circle with Romney: He started out as the conservative candidate, pivoted toward the CEO/change candidate, and now he's back to emphasizing his conservatism. Only this time, it's conservatives, faced with a McCain nomination, who are asking him to be that.

"McCain Gets Schwarzenegger's Endorsement" (Liz Sidoti, Associated Press) Flanked by Rudy Giuliani and Gov. Arnold Schwarzenegger yesterday in Los Angeles, John McCain is basking in a moderate show of support.

"Obama Raises $32 Million in January" (Jim Kuhnhenn, Associated Press) That's not for the last quarter -- that's for January. Many expect the Democratic race to last beyond Feb. 5, which means Obama will need all the money he can get to compete with a strong Clinton machine.

"Former President Shows Calmer Face in Campaign" (Katharine Seelye and Raymond Hernandez, New York Times) Bill seems to have had his wings clipped lately. Going into South Carolina, the former president let loose on opponent Obama and it backfired. He's still on the trail, but he keeps his comments squarely on his wife's credentials.

"Romney Launches Super Tuesday Ad Barrage" (Dan Morain and Scott Martelle, Los Angeles Times) Romney has launched a multi-million ad buy in Feb. 5 states, pouring $1 million into California alone. But history has shown that Romney's saturation of the market rarely pays off in the end.

"Obama '04 At Odds With Obama '08" (Jen Haberkorn, Washington Times) A preview perhaps of how the Republicans might go after Nominee Obama.

"World Captivated by US Presidential Race" (William Kole, Associated Press) Seems Obama is winning the global race, although the Russians apparently prefer a Republican in the White House. As the presidential campaign moves forward, the world watches.

Get today's other election stories at RCP's Politics and Election page.