WASHINGTON — Eight Republican presidential candidates will debate under the shadow of Ronald Reagan’s Air Force One jet in California tonight.

It’ll be the first major Republican presidential debate without Tim Pawlenty and with Texas Gov. Rick Perry, who joined the race on Aug. 13 and has vaulted to the front of the pack in many national and statewide polls.

He’s done so at the expense of Michele Bachmann, who rode a wave of tea party appeal to victory in the Iowa straw poll. That victory has not translated into new support, as her polling numbers have fallen steadily and much of her base has run to Perry.

Lost in the battle for the tea party is Mitt Romney, who for months — if not years — was seen as the front-runner for the party’s nomination in 2012. After staying relatively quiet, he’s likely to engage Perry with the hopes of stealing some support back.

The summer campaign for Iowa is over; the fall campaign for Iowa, New Hampshire, South Carolina, Nevada and the other 46 states kicks off at the Ronald Reagan Presidential Library tonight (7 p.m. CT on MSNBC, and streaming live at politico.com). It's the first of three Republican debates this month. Here’s what to watch for:

Can Michele Bachmann rebound? Bachmann was the big winner in the summer’s first debate in June, announcing on-stage that she had filled paperwork to run for president. Between that announcement and Pawlenty’s disastrous performance (remember Obamneycare?), Bachmann came out of Manchester, New Hampshire looking pretty good.

She followed it up with a steady-but-forgettable showing in Ames ahead of the straw poll: she absorbed and rebutted Pawlenty’s attacks well, and used the audience’s boos to quash a question about whether her religious views require her to “submit” to her husband. But beyond that, it wasn’t a particularly memorable event.

Now, Bachmann is behind in the polls and bleeding supporters to Perry. That sounds an awful lot like what Pawlenty was facing — against Bachmann — in Ames.

But Bachmann has something Pawlenty never did: a base of support that’s already catapulted her to a statewide straw poll victory. She needs an aggressive strategy tonight — if she can emphasize her tea party chops and diminish those of Perry, she might be able to convince some of those old supporters to give her another shot. If she can bring Perry back to the pack just enough to make him sweat, that would have to be seen as a win for Bachmann.

How well will Rick Perry perform? Some of Perry’s early support can be attributed to an initial bump in the polls exciting new candidates earn before voters get to really know them. He’s also gained support from those who say they like his style of personal interaction with voters.

But Perry has never had to directly fight with his fellow candidates for voters’ adoration until now. He’ll have a huge target on his back and the least presidential debate experience of anyone on the stage. How he responds to the pressure is likely to be a top national storyline tomorrow morning.

If Perry can keep his cool and handle the onslaught he’s likely to receive from the other candidates, he’ll be off to a good start. From there, he’ll have his best opportunity yet to appeal to a broad audience on national television. He doesn’t need to be flashy to be impressive — a steady, workman-like performance will only solidify his frontrunner status.

What in the world does Mitt Romney do now? Mitt Romney’s in a very tenuous spot. His biggest constituency is the moderate, business-oriented wing of the Republican Party. If, in an effort to curtail Perry’s surge, he moves too far to the right, he risks alienating the base he’s already established. But he can no longer afford to keep quiet, like he did during the two major debates over the summer, when he let Pawlenty self-destruct in New Hampshire and then watched as he and Bachmann beat each other up in Ames.

Romney’s best bet (and likely strategy) is to hammer away at the jobs plan he introduced yesterday. While it’s a reasonably standard Republican economic proposal, at 59-points and 160 pages long, it’s the most thorough proposal any of the candidates have yet released.

It’s no coincidence Romney introduced the plan a day before the debate and two before President Barack Obama’s much-anticipated jobs speech to Congress on Thursday. Romney wants to present himself as the candidate best prepared to take on Obama and do the job in the Oval Office. He’ll need to hammer away at that tonight if he hopes to stop Perry.   

Can the other candidates break through? Speaking of jobs plans, former Utah Gov. Jon Huntsman is likely to plug his during the debate. He launched his campaign to high hopes from moderate Republicans unhappy with the rightward swing of the party, but he’s yet to gain any traction with likely primary voters. September’s three presidential debates might be his (last best?) shot to garner support.

Ron Paul, the second-place finisher in the Iowa straw poll, will likely turn in his normal, fiery libertarian debate performance. Whether it’s strong enough to break through the Romney, Perry and Bachmann storylines is a bigger question.

A trio of other candidates — Newt Gingrich, Herman Cain and Rick Santorum — are managing to hang around, but will need to have stellar performances here on out if they hope to have any impact when the real voting begins in February.

What questions will be posed? Fox News’ debate moderators in Ames offered an impressive array of questions for the candidates to answer, and the anchors really pressured them to account for controversial statements and past policy positions. If debate sponsors Politico and NBC did their homework, they’ll have the chance to do the same tonight.

Bachmann will almost certainly get a question on $2-a-gallon gas, which she’s promised to deliver if she’s elected president. Since the last debate, she’s also floated drilling for oil in the Florida everglades and eliminating major federal programs like the Department of Education, both of which could come up during the debate. She also joked that August’s earthquakes and hurricanes were messages from God, so that could be pretty good fodder for a debate moderator.

Perry’s managed to mainly keep his nose clean since joining the race. One statement that could come up, however: he warned in August that it would be treasonous for the Federal Reserve chairman to print more money during a recession. Perry’s also likely to hear questions about his book, “Fed Up!” which espouses controversial opinions like Social Security a “Ponzi scheme.”

Romney has a small fire to put out when it comes to the planned expansion of his California beach house. Along those same lines, Gingrich might need to answer for a Hawaiian campaign stop that just happened to coincide with his wedding anniversary. It’s really up in the air whether the moderators will think the public cares enough about such behind-the-scenes issues to ask questions about them in a debate.

But no matter what they do choose to ask, here’s hoping we’ve seen the last of “This or That” for the election cycle.

Devin Henry can be reached at dhenry@minnpost.com.