Former New York City mayor Rudy Giuliani found himself the target of criticism from rival Mitt Romney in a lively and substantive debate that highlighted the diversity of the Republican field and the political cross-pressures they confront.

First time debater Fred Thompson seemed well prepared and did not give in to fruity abstractions when talking about obtuse topics. Some of his rivals may have assumed that he would wither under tough questions from the moderators: he did not. Some journalists may have assumed that he would slouch or tire; he seemed energetic. If this was a test, artificial as it may have been, Thompson passed it. He demonstrated that his campaign has density. He did not fall for any of the traps that the moderators laid for him.

The exchange between Romney and Giuliani on the line item veto will clearly go down as the soundbite moment of the debate. Haymakers flew in both directions. Later, in an e-mailed statement, Giuliani’s campaign enlisted former Solicitor General Ted Olson to lash Romney:

"The Clinton Administration line item veto was unconstitutional. Anyone who does not understand that has not read the Supreme Court's opinion striking it down and does not have a clear understanding of the Constitution."

Later, Romney’s rivals immediately pounced on what they saw as a gaffe: Romney, responding to a question about whether President Bush was obligated to get Congress’s permission before attacking Iraq, said: “"We’re going to let the lawyers sort out what he needed to do and didn’t need to do." Romney did give a stronger response on military action on the back end.

Surprisingly, it was Fred Thompson who said that whether or not the President had to get Congress’s permission, it ought to – even in close calls. “You should go to Congress, whether it’s legally required or not.”

The candidates dodged a question about ethanol; the candidates said they supported heavy subsidies for that industry, which disproportionately benefit farmers in Iowa. Romney, a free trader, acknowledged he believes in “domestic supports” for the country’s food industry.

Republicans looking for differences among the candidates found a few. Huckabee, Tancredo and
Hunter opposed the current round of trade agreements’ he rest of the candidates supported it.
Huckabee and Hunter explained their support of the “Fair Tax.” The other candidates oppose it. Romney wants a line item veto; Giuliani thinks a constitutional amendment is needed. Romney, McCain and Giuliani seemed to be less gung go about getting Congressional approval for strategic strikes than Thompson.

Props to, in no particular order:

Hillary Clinton: for a guest appearance as the Democratic presidential nominee

McCain: for tailoring his appeal to heartland Republicans; for giving props to Giuliani; for speaking about health care and jobs; for mentioning “legacy costs.:” For repeating his opposition to ethanol subsidies. For admitting that he doesn't know enough about interest rates to say whether the Fed should cut rates.

Giuliani, for repeatedly invoking Hillary Clinton and her allegedly extravagant, nefarious liberal schemes. And for showing off his sunny optimism.

Hunter: for distinguishing himself, finally, in a debate, by defining himself as the race’s protectionist.

Romney: knowing the ins and outs of the Michigan economy; for landing a punch about the line item veto; he got a full minute and a half to explain his health care plan.

Huckabee: for nothing in specific, but everything in general. For admitting that he might not veto SCHIP because of political considerations and substantive considerations.

Brownback: for saying “This place rocks.” And “Don’t pick on my mother.” He got applause for saying he'd support a nominee that is "pro growth" and "pro life."

Thompson: for eclipsing (artificial) low expectations; for holding his own. For giving specifics about how he’d solve the long term solvency problems of Medicare and Social Security. He seemed to give the best answer in re: unions.

Tancredo: for poking fun at his obsession with illegal immigration.

Paul: for making the anti-monetarist argument and getting applause for it.

Chris Matthews and Maria Bartiromo: for letting the candidates talk; for making the debate about the candidates; for asking the question about labor unions.

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