DAY IN A NUTSHELL
John McCain and Barack Obama engage in verbal clashes over comments made by Mr Obama about Iraq in last night's Democratic debate. Hillary Clinton campaigns in Ohio ahead of the state's primary on 4 March. Civil rights leader and Georgia congressman John Lewis formally endorses Barack Obama, having previously backed Mrs Clinton.
"I have some news [for Barack Obama] - al-Qaeda is in Iraq. Al-Qaeda is called al-Qaeda in Iraq. My friends, if we left, they wouldn't be establishing a base... they would be taking a country"
John McCain reacts to Mr Obama's comments on Iraq in last night's TV debate
"I have some news for John McCain... there was no al-Qaeda in Iraq until George Bush and John McCain began the Iraq war"
Barack Obama hits back at John McCain
"I think a lot of people who watched [last night's debate] would come away and feel very positive and comfortable with what I said and what I presented as my credentials and my positions on these issues, and I thought there were some real contrasts that were drawn."
"Republicans owe Hillary our gratitude. She has road-tested several versions of attacks on Obama that don't work."
Tony Blankley, Washington Times
If the Democratic race is still going after the 4 March primaries in Ohio and Texas, then the next big contest will be the Pennsylvania primary on 22 April.
As in neighbouring Ohio, observers expected the demographic make-up of Pennsylvania - with its large blue-collar workforce - to favour Hillary Clinton.
A Quinnipiac poll published today suggests that Mrs Clinton does indeed hold the lead there - but only just.
It gives her 49%, six points ahead of Barack Obama on 43%.
The last Quinnipiac poll - published on 14 February - gave Mrs Clinton a 16-point lead, with 53% to Mr Obama's 36%, so the Illinois senator appears to be narrowing the gap in the state.
Speechwriter Mark Salter (L) shows more signs of sleep-deprivation than his boss, John McCain, on the senator's campaign bus