When Texas Gov. Rick Perry jumped in the 2012 presidential race, and Tim Pawlenty exited, "some pundits were quick to declare the GOP field filled," says Linda Feldmann in The Christian Science Monitor. "Not so fast." If anything, the buzz over other would-be Republican contenders has only increased, fueled by rumor, speculation, and the insinuations of the hypothetical candidates themselves. Here, a look at five prominent Republicans who might still come in off the sidelines:

1. Sarah Palin
The Republican Party's 2008 vice presidential nominee has been touring Iowa in a campaign-style bus, has released a campaign-style video, and maintains a schedule "that looks like that of a candidate, not a celebrity," said GOP strategist Karl Rove on Fox News. "I think she gets in." Of course she's getting in, says Andrew Sullivan at The Daily Beast, whether the GOP wants her to or not. How can you watch her new video "and believe she isn't serious?" Well for one thing, there's "zero indication that she's organizing staff or potential donors behind the scenes," says The Christian Science Monitor's Feldmann. This looks to me like nothing more than another publicity blitz for Brand Palin.

2. Paul Ryan
The Wisconsin congressman is vacationing in Colorado with his family, reportedly trying to decide whether to join the race, says Toby Harnden in Britain's Telegraph. Several powerful Republicans are urging him to jump in, and according to The Weekly Standard, his wife is "on board," which is a "very big deal." Indeed, s
ources say the GOP's budget guru is close to "overcoming his prior reluctance," says Michael Medved at The Daily Beast, because of the "painfully apparent weakness and vulnerability" of both President Obama and his GOP challengers. Hold on, says Chris Cillizza in The Washington Post. The speculation is great for Ryan's career, but "most plugged-in GOP observers" still think he's sitting this one out.

3. George Pataki
A spokesman says the former New York governor "is strongly considering entering the crowded race for the Republican presidential nomination," according to NY1. Huh? says Doug J. at Balloon Juice. "Pataki has no charisma and isn't especially conservative," which makes him a "more boring, less accomplished [Jon] Huntsman." On the other hand, he's "already been campaigning on the DL" in independent-minded New Hampshire, where he could potentially give Mitt Romney a run for his money.

4. Rudy Giuliani
Pataki isn't the only New Yorker mulling the question, says Scott Conroy at RealClearPolitics. "Though he has largely been ignored as a viable potential candidate," former New York City Mayor Giuliani is "seriously looking at" a run, according to top aide Jake Menges, and is currently looking for reassurances that he could win. In that case, he should save his time and money, says Jason Linkins at The Huffington Post. His 2008 run flopped, and the 2012 primaries will be even tougher for GOP moderates. Hold on, says Kyle Leighton at Talking Points Memo. In an early August Gallup poll, Giuliani was the only Republican who beat Obama. If Republicans want to win, they might want to give Giuliani a closer look.

5. Chris Christie
The New Jersey governor has repeatedly — and colorfully — denied he is running for president, but some Republicans haven't given up hope, says Amanda Carey at The Daily Caller. Many ex-members of Tim Pawlenty's staff have held off on jumping to another campaign because they're "very anxious to have Christie officially place his hat in the ring." Enough already, says George Will in The Washington Post. Christie won't run. "He relishes being America's Caesar — its most powerful governor" — and he has "four children, ages 8 to 17, he will not abandon for presidential politics."