Howard Megdal thinks a new GOP rule which says that any primary or caucus held before April 1 must allocate delegates proportionally could lead to a brokered convention.

“From April 1 on, the winner-take-all primary and caucus states will vote. That means a weak front-runner can earn victories in early states without taking a commanding share of that state’s delegates, while several challengers can lose, but still rack up a decent delegate total… 1,163 of 2,380 delegates will be selected before a single winner-take-all primary is held.”

“Rather than settle for a nominee incapable of generating enthusiasm,” Republicans could use their national convention “to find a candidate more in tune with the Republican voters” including “a compromise candidate who hasn’t been in the race at all.”

During last night’s GOP presidential debate, Michele Bachmann claimed that 15 Pakistani nuclear sites were vulnerable to jihadist attacks, and that six of them had already come under some form of Islamist attack. No U.S. official had ever said that before and Bachmann serves on the House Intelligence Committee.

National Journal concludes the new facts “represent either a news-making leak of previously unknown classified information or another in her recent series of seemingly-random, and highly inaccurate, public comments.”

Out next week: Playbook 2012: The Right Fights Back by Mike Allen and Evan Thomas, the first in a series of e-books on the 2012 presidential election.

According to a publicist’s email, “It’s loaded with juicy scoops and razor-sharp analysis and explains with an insider’s precision the intrigues and the plotting, the ground games and the quests for cash.”

TV show host Jimmy Fallon apologized to Rep. Michele Bachmann for a song played as the presidential candidate walked on stage for her interview on his late night show, CNN reports.

As Bachmann walked out to greet Fallon, the show’s band played a song by Fishbone called Lyin’ Ass Bitch.

A new Pew Research survey finds no evidence that Mitt Romney’s Mormon faith “would prevent rank-and-file Republicans, including white evangelicals, from coalescing around him if he wins the GOP nomination. Rather, the same Republicans who may have doubts about Romney’s faith are among the most vehement opponents of Barack Obama.”

Key findings: “Fully 91% of white evangelical Republican voters say they would back Romney over Obama in a general election matchup, and 79% would support Romney strongly. Overall, white evangelicals would be among the strongest Romney supporters if he is the GOP nominee challenging Obama next fall.”

“Representatives for leading social conservative groups in Iowa held a secret meeting Monday as part of an effort with one main goal: find and support a Republican presidential candidate who can stop Mitt Romney in Iowa,” CNN reports.

“The idea: avoid splintering the conservative vote in the state by rallying around one GOP rival who could win Iowa’s Jan. 3 caucus and then challenge Romney in New Hampshire and the other early voting states.”

Mitt Romney will announce the endorsement of Sen. John Thune (R-SD), the Washington Post reports, “a rising star in the Republican Party who had weighed a White House bid of his own before deciding to stay in the Senate and move up in his party’s leadership.”

The Daily Beast has video clips of the best parts from last night’s Republican presidential debate.

Newt Gingrich failed to qualify for the Missouri Republican primary, the Los Angeles Times reports.

The filing requirements were not particularly onerous: A $1,000 check and some paperwork were all that’s needed. But Gingrich failed to file by the deadline.

“Missouri’s primary is a ‘beauty contest,’ meaning that no delegates will be awarded. The state Republican Party will hold caucuses in March for that purpose. However, Missouri is a major state, and the nonbinding contest will be the only primary in the country between the Florida primary on Jan. 31 and the Arizona and Michigan primaries on Feb. 28. Candidates wishing to maintain their momentum, and media visibility, through that dry spell in February may well see Missouri as a place to compete for bragging rights.”

Mitt Romney, as in previous debates, was the best prepared and gave solid answers to all questions. But this time he had a worthy adversary in Newt Gingrich, who is clearly emboldened by his high polls numbers (and his own intellect). The thing to watch: Will Gingrich’s “humane” stance on immigration be the issue Romney can use to knock him off in Iowa?

Jon Huntsman had his best debate yet. It’s clear he’s given significant thought to these issues while living abroad as an ambassador.

Michele Bachmann also did reasonably well but strangely asserted that President Obama met with Iranian leaders. Nonetheless, it was her best debate in weeks.

Herman Cain is clearly out of his league. His solution to every problem is to get smart people in the room to decide. There’s clearly stuff still twirling around in his head.

Rick Perry didn’t implode but he didn’t distinguish himself either. He used nearly every answer as an opportunity to attack President Obama without actually offering workable solutions.

Rick Santorum was an afterthought.

However, it was most fun to watch Ron Paul. His positions are clear, consistent and interesting. On issues like the Patriot Act, drug trafficking and the Iraq war, he highlights a major split between the libertarian and neo-conservative wings of the Republican party. Paul’s problem is that his wing is probably no more than 20% of the Republican party today.

It’s not clear to me who actually “won” the debate. But it is clear that Romney still hasn’t pulled away from the pack despite his string of solid performances.

Just published: Mitt Romney: An Inside Look at the Man and His Politics by Ronald B. Scott.

Ben Smith notes the book takes a closer look at the Romney family. Romney’s eldest sister Jane, an actress who lives in Los Angeles is described “the Billy Carter of the Romney family” in part because she openly backed Sen. Barbara Boxer (D-CA) and campaigned for California Gov. Jerry Brown (D). She also had a “very acrimonious divorce” from a nephew of the head of the Mormon church.

Jane Romney apparently “is eager to have a visible role on her brother’s campaign which, in turn, is eager to keep her busy and out of trouble.”

Weekly Standard: “It’s becoming increasingly hard to say whether Newt Gingrich or Mitt Romney, the two leading Republican presidential candidates, would fare better against Barack Obama.”

“Each of these two leading GOP candidates certainly has his strengths in an electoral vein. Romney consistently fares better than Gingrich among independents — the block of voters who will likely decide the election — while Gingrich’s support among the Tea Party could help energizing the party’s base, which in turn could influence independents (who are generally more apt to rally behind candidates who have the enthusiastic support of others — a fact that seems to be particularly true for GOP candidates across the years).”

Gallup: “Newt Gingrich now leads all of his Republican presidential rivals in garnering positive image ratings from Republicans and Republican leaners nationwide — marking a first for 2011. His +20 Positive Intensity Score gives Gingrich a sizable lead over Herman Cain, in second with +14, and Mitt Romney, in third with +11.”