With Alaska Gov. Sarah Palin set today to introduce herself to the American public and formally accept the GOP nomination for vice president, Republicans believe they might have found the solution to several political challenges facing GOP candidates up and down the November ballot.

Particularly in the Mountain West and the Southwest — where Democratic presidential nominee Sen. Barack Obama (Ill.) and Democratic House and Senate candidates are threatening historically conservative strongholds — Republicans expect Palin to blunt this attack, generating voter turnout and activist participation that benefits GOP Congressional candidates while helping Sen. John McCain (R-Ariz.) overcome his sometimes rocky relationship with the Republican base.

The Democrats’ political hurdles are less steep and fewer in number. But they have reacted similarly to Sen. Joseph Biden’s (Del.) selection as Obama’s running mate, expecting him to compensate for the occasionally tepid support the Democratic presidential nominee has received from key voting blocs, including working-class voters, Catholics and Jews.

“The choice of Sarah Palin has dramatically transformed the GOP’s prospects for November,” said David Gilliard, a Republican consultant based in Sacramento, Calif. “Our conservative volunteers and donors were in the doldrums until Sen. McCain made the bold stroke of choosing Gov. Palin as his running mate.”

Democrats are running competitive candidates in several races out West in regions that have historically been friendly territory for the Republicans, including Alaska’s Senate and at-large House seats; Colorado’s 4th district and open Senate seat; Idaho’s 1st district; New Mexico’s 1st and 2nd districts; Nevada’s 3rd district; and Wyoming’s at-large House seat. With the exception of Idaho, Wyoming and now probably Alaska, Obama is competing for electoral votes in each of those states, in addition to running strong campaigns in Montana and North Dakota.

A Republican Party official confirmed that Palin is viewed as key to McCain’s effort to keep these states in the GOP column on Nov. 4. Republican strategists involved in competitive House and Senate races describe Palin as a net plus in their campaigns, as they work to withstand what will be an extremely well-funded attempt by Congressional Democrats to repeat the wave of 2006.

Bob Balink, a 66-year-old Colorado delegate to the Republican National Convention in St. Paul, Minn., said adding Palin to the GOP White House ticket could prove crucial to McCain’s prospects of holding off Obama in the Centennial State and aiding Republicans who are running downballot. Balink said Palin brings the kind of excitement to the ticket that he speculates could signal the resurgence of a GOP that has taken several hits since President Bush was re-elected in 2004.

“I don’t think the state is as close as people say,” said Balink, a Colorado Springs resident who is also the elected county clerk and recorder of El Paso County. “But in case I’m totally wrong on that, [Palin] will be a tremendous boost to making sure Colorado remains a red state.”

Democratic strategists involved in competitive House races in Maryland, Michigan, Ohio and Pennsylvania expect Biden to do the same thing for their candidates. Although Obama is still running either even or ahead of McCain in these states, his poor performance with the blue-collar and Catholic voters in some of the competitive House districts in these states could prove to be a liability.

Despite being reliable Democratic voters, some Jewish voters also have some anxiety over Obama — particularly what his administration would mean for Israel. Biden is expected to help shore up support for Democrats on this front as well.

The affected seats include some where Democrats hope to upend GOP control, including Maryland’s open 1st district; Michigan’s 7th and 9th districts; Ohio’s 1st, 15th and 16th districts; and Pennsylvania’s 3rd. In the Keystone State’s 10th and 11th districts, the Democratic incumbents are playing defense.

In Pennsylvania’s 11th district, which includes Biden’s hometown of Scranton, Rep. Paul Kanjorski (D) put out a statement hailing Obama’s selection of Biden as his running mate just minutes after Obama announced his choice.

Former Michigan Gov. and ex-Rep. James Blanchard (D), an Obama/Biden campaign surrogate, expects Biden to be an asset for the Democratic ticket in middle-class districts throughout the country. But Blanchard also predicts that Biden will help generate Democratic victories in the White House contest and in Congressional races in districts like Michigan’s 9th, where most voters are well-educated and the Jewish vote is crucial.

“Joe will help strengthen the campaign in blue-collar areas of Michigan,” Blanchard, who lives in the 9th district, said in a telephone interview. “I have to also believe he will translate in Pennsylvania and Ohio.”

Democratic strategists involved in Senate races say that, with the exception of Kentucky, the GOP seats that are up this cycle that Democrats are targeting tend to be in states that are already strong for Obama and do not necessarily lend themselves to Biden’s personal appeal.

However, with the Bluegrass State expected to go heavily for McCain in November, these strategists don’t expect Biden to spend much time there, although Senate Minority Leader Mitch McConnell (R-Ky.) remains a top Democratic target.

McCain’s selection of Palin to be his running mate was greeted with resounding enthusiasm by the same base Republican voters who have long been suspicious of the Arizona Senator’s politics and resentful of him for taking positions on key issues that were at odds with many in the GOP.

Should Palin, a first-term Alaska governor who is relatively unknown, survive the initial media scrutiny unscathed — and perform well in tonight’s acceptance speech — Republicans believe she could prove to be a greater boost to the GOP ticket than running mates typically are. Palin’s next test will be her effectiveness on the campaign trail and the vice presidential debate with Biden.

Meanwhile, Palin thus far has accomplished the crucial task of motivating base Republicans to work hard on McCain’s behalf — which, unlike 2004 when they worked hard for Bush, had been viewed as an uncertainty at best and unlikely at worst. Republicans familiar with the inner workings of the McCain/Palin campaign report an immediate and significant uptick in fundraising and offers to volunteer in the aftermath of Palin’s selection.

However, some Republican strategists caution that Palin might only serve to ensure GOP victories in solidly conservative districts that are competitive this year but shouldn’t be — and doesn’t necessarily broaden the party’s appeal.

Among those conservative districts are Idaho’s 1st, where freshman Rep. Bill Sali (R) is facing stiff competition from businessman and 1996 Senate candidate Walt Minnick (D), and Wyoming’s open at-large House seat, where 2006 Democratic nominee Gary Trauner is running against former state Treasurer Cynthia Lummis (R).

Still other Republicans argue that the Palin pick was politically brilliant and will mean more to the ticket than ensuring victory in heavily GOP areas.

“I think it was more of a global pick,” one Republican strategist said. “Not only does she resonate on Western issues, but she reaches out to the pro-life base and that center right consortium where middle America sits. She really dials in on that.”