Republican presidential candidate Newt Gingrich refers to President Obama as “the food stamp president,” and a “Saul Alinsky radical” and says the president takes advice from people who “don’t like the classical America.” He constantly promises to take on Obama in Lincoln-Douglas style debates if he wins the nomination and jokes he will let the president use a teleprompter, a regular GOP attack line that implies Obama can’t give a speech without help.

On the other hand, his chief opponent, former Massachusetts governor Mitt Romney, barely can stomach calling Obama a socialist as other Republicans do and rarely invokes the sharp, anti-Obama rhetoric of the Tea Party.

WATCH: THEGRIO’S JOY-ANN REID DISCUSSES GINGRICH’S FIXATION ON FOOD STAMPS ON MSNBC

Is Romney too meek in his Obama-bashing to win the GOP primary? Since Obama’s election, many Republicans have not just taken on his policies, but criticized the president in a way that many Democrats feel borders on showing disrespect to him. The finger-pointing at Obama by Arizona Republican Gov. Jan Brewer Wednesday was the latest in what some Democrats view as over-the-top rhetoric and behavior by Republicans.

Is that attitude what it takes to win over conservative voters? In polls, it’s impossible to determine exactly what causes the resistance to former Massachusetts governor Mitt Romney, who lost the conservative and Tea Party vote in Iowa and South Carolina, blunting his progress toward the GOP nomination. A new NBC News/Wall Street Journal poll showed Gingrich leads Romney by 30 points among “very conservative” voters and 25 among Tea Party supporters.

Romney has taken moderate stands on health care and other issues in his career, but so has Gingrich, as many conservatives note. It was Gingrich, not Romney, who was working on climate change legislation with Democrats only a few years ago.

But throughout this campaign, Romney has struggled to consolidate the conservative vote against an alternative who uses more flamboyant rhetoric to take on the president. Donald Trump suggested Obama was not born in the United States, Herman Cain questioned the president’s blackness, Gingrich casts the president as almost anti-American. One-time candidate Tim Pawlenty struggled to connect with GOP voters even as he is conservative as his rivals in part because he came across as polite and dull to voters and largely avoided fiery, anti-Obama rhetoric.

That contrast has created a campaign in which Romney does very well among upper-income, moderate, non-Tea Party Republicans. But Gingrich is now the champion of Tea Party, anti-establishment Republicans who want someone not just to defeat Obama, but give him a figurative punch in the mouth along the way.

“The Romney campaign has been the cucumber sandwiches on silver trays campaign,” said GOP strategist Alex Castellanos told Politico recently. “Newt is running a torches and pitchforks campaign. Who do you think Republicans would want to storm the castle with? When you’re storming the castle you don’t care if your leader has slept around, is on his 50th wife — you just want somebody who says, ‘Let’s go kill them!’”

Romney and Gingrich are effectively tied in the polls in Florida, and a Romney win there would restore him as a heavy favorite to win the GOP nomination. But a loss would call into question the approach of the former governor, who has largely stuck to blasting Obama’s stewardship of the economy and questioning Gingrich’s conservative credentials.

Romney has said he is more electable than Gingrich, and polls show he does better against Obama than Gingrich. And his more restrained rhetoric may help with that. But Romney may have to shift his approach to get to the general election.

Follow Perry Bacon Jr. on Twitter at @perrybaconjr