Republican U.S. Senate hopeful Todd Akin stuck to his principles during his final  rally in St. Louis, as he reaffirmed his opposition to the 2008 bank bailout and promised, if elected, to “get us out of the United Nations.”

“A proven record beats talk and promises,’’ Akin said, igniting applause from about 100 supporters gathered Friday night in a hotel ballroom in Westport Plaza. “I believe this is our calling now.”

The St. Louis County stop capped a week-long string of events througout the state, dubbed the "Leading With Courage Tour."

The six-term congressman from Wildwood pressed to his audience – many of them home-schoolers, a longtime supportive bloc – that it was up to them to help him on Tuesday edge out his two chief GOP rivals, St. Louis businessman John Brunner and former state Treasurer Sarah Steelman.

All three are vying for the chance to challenge U.S. Sen. Claire McCaskill, D-Mo, in the fall.

The contest for the GOP nominee, said Akin, is “absolutely too close to call.”

Across the state, in suburban Kansas City, Steelman was making a similar appeal as she dished out barbecue Friday night with a GOP celebrity, former Alaska Gov. Sarah Palin.

According to the Kansas City Star, 700 people packed the grounds of a Cass County farm to hear Palin, sporting a Superman logo, tout Steelman as a candidate with “ the backbone to stand up for what’s right.”

Palin -- who also appears in a pro-Steelman TV spot – reprised her portrayal of Steelman as a fellow “mama grizzly’’ who isn’t afraid to buck party leaders.

Neither Akin nor Steelman made public mention of Brunner, who completed his last statewide tour on Thursday by leading reporters and allies on a tour of his former family-owned company, Vi-Jon.

The wealthy businessman has been shown in the latest polls to have a lead – although it varies from poll to poll.

In primaries, hard to predict turn out

The problem, consultants and analysts agree, is that it’s tough for many pollsters to determine who will actually turn out in a partisan primary.

If turnout is low, that’s usually an indication that the ballots are largely from diehard party loyalists. If higher than expected, the turnout could signal that independents have decided to weigh in – which could dramatically change the predicted results.

Missouri Secretary of State Robin Carnahan is predicting a statewide turnout of just under 26 percent on Tuesday, which would be slightly higher than the 23 percent turnout in the August 2010 primary. The percentage is based on reports from local election officials around the state.

But that prediction could be somewhat optimistic, since the 2010 primary vote – especially among Republicans – appeared to be bolstered by Proposition C, a ballot measure to exempt Missouri from the federal health insurance changes mandated under the Affordable Care Act.

This time, less public debate seems to surround Tuesday’s only ballot measure, a proposed constitutional amendment dealing with prayer and religious conscience.

In August 2008, the official prediction for the primary had been 30 percent – reflecting the seemingly high voter interest. But only 18 percent actually showed up at the polls.

Few 'crossover' votes expected

St. Louis County Democratic elections director Rita Days is predicting only a 20 percent turnout on Tuesday, while her counterpart in St. Louis – Mary Wheeler-Jones – expects about a quarter of the city’s voters to take a ballot. Wheeler-Jones cites the spirited contests for city treasurer and in several legislative districts.

In Missouri, voters don’t register by party, so anyone can ask for any party’s ballot during Tuesday’s primary. But they can only vote for one party’s candidates, which can pose a dilemma.

Some political activists predict the Republicans’ hot contest for the U.S. Senate may attract people who might otherwise vote Democratic or not vote at all.

In St. Louis, some Democrats privately say they’re glad there’s some competitive Republican contests because that could make it less likely that GOP-leaning city voters will take a Democratic ballot (known as “crossover voting”)  to help choose the victor in the combative race between U.S. Reps. William Lacy Clay and Russ Carnahan, who have been tossed into the same 1^st congressional district.

Clay and Carnahan are spending the weekend scrambling for votes. Clay, for example, went door-to-door Saturday with Mayor Francis Slay in the Central West End. The mayor also is featured in Clay's new TV adm which takes a swipe at Carnahan.

Carnahan’s campaign disputes the ad's assertions, which include a portrayal of Carnahan as pro-tea party -- something his campaign finds ridiculous since Carnahan was targeted for defeat by tea party groups in 2010.

Carnahan's last-weekend campaign plans include Sunday morning stops at several African-American churches.

McCaskill closely watching GOP primary

(Start of update) At a Saturday morning gathering of volunteers in St. Charles, McCaskill quipped that Tuesday was going to be like Christmas. "I'm finally going to get to unwrap a package and see what's in it,'' she said.

By that, the senator explained, she means she'll finally know against whom she will compete in November.

McCaskill told the volunteers, as she has for weeks, that all three of her potential Republican rivals share the same conservative views. "They all want to privatize Medicare. They all want to privatize Social Security. And they want the government to get out of the student loan business, so only the rich can afford to go to college," she said.

But several volunteers said that most of the questions and concerns they hear from likely voters deal with the federal health insurance changes in the Affordable Care Act., Many are angry and confused, and some hang up, several volunteers said.

McCaskill replied, "There is a lot of misinformation out there'' that she hopes will be debated during the final three months leading up to the November election.

But for now, she said, "I'm just anxious for Tuesday, and ready for it to be one-on-one."

(End of update)