Claire McCaskill, Emanuel Cleaver and Jay Nixon are among the most popular politicians ever in Missouri.

All three have served in a variety of public offices for more than 25 years. And next Tuesday — because of their track records but also because of the subpar qualifications of their opponents — all three deserve to be re-elected.

And yet....

• McCaskill is in a tight race with Republican Todd Akin for her U.S. Senate seat.

That’s despite the fact McCaskill has multiple advantages. She has millions more in donations than Akin to spend on ads. Her opponent has been abandoned by his own party’s leaders. And Akin has made nationally ridiculed and inane comments about rape.

Still, Akin and his ultra-conservative views on federal spending, abortion and other issues are beloved throughout the state’s rural areas.

Polls also show that voters have a fairly high negative perception of McCaskill (Akin also has high negatives). Much of McCaskill’s problems can be linked to the fact that Missouri has turned increasingly Republican, hostile to policies — such as Obamacare — which she backed.

McCaskill often speaks frankly, a trait I admire in a politician, but one that can come across as brusque and high-handed to others. Add her problems with paying taxes on time for a private airplane and the continued attack by opponents on her husband’s many business connections to public spending, and McCaskill looks more like an out of touch Washington politician than she really is.

In the end, McCaskill probably will win partly because Akin is the weakest candidate Republicans could have selected in their primary in a state that will give Mitt Romney a large victory over President Barack Obama.

• Cleaver might have his closest race ever against Republican Jacob Turk in the battle for the U.S. House’s 5th District seat representing a large part of the Kansas City area.

Sure, the Democratic incumbent previously defeated Turk in 2006, 2008 and 2010.

But Cleaver — who seldom has deigned to do much campaigning since his first tough House election in 2004 — and his supporters ought to be more wary this year.

The congressman is in a newly configured district that might be less friendly to Democrats. His victory margin over Turk has declined from 32 percentage points in 2006 to 9 percentage points in 2010. Cleaver is the subject of a widely reported lawsuit over a car wash he owns, in which lots of federal tax dollars are at risk because of an unpaid loan.

More positively, Cleaver has delivered soaring and needed rhetoric on behalf of bipartisanship in Washington. He has brought home federal funds as earmarks to rebuild Kansas City’s urban core.

When the votes are counted Tuesday, expect him to survive the latest challenge from an undistinguished GOP candidate.

• Nixon could fall victim to a late surge from Republican Dave Spence in the governor’s contest.

Don’t believe me? You’ve got good reasons. Nixon has won all but one of his races for state offices by around 20 percentage points the last two decades (though he was swamped in two U.S. Senate bids).

However, his lead over Spence had dwindled to a six-point spread in the recent Mason-Dixon Polling & Research survey in The Star, far down from earlier leads of up to 20 percentage points.

Nixon is a flexible politician. He’s a Democrat who tacks to the right to look like a Republican on fiscal matters. He’s shown no spine on Missouri’s laudable cigarette tax increase plan on Tuesday’s ballot, refusing to endorse it even though it would raise money for schools and cut smoking rates. He’s too often silent and malleable on his duties, which include being a stronger supporter of better funding for education and health care.

Still, Nixon should come out ahead on Election Day, largely because Republicans sent in to battle a candidate (Spence) with little name recognition and little idea of what he would do as governor.

If you like McCaskill, Cleaver and Nixon, you’ll almost certainly see some good news next Tuesday.

If you don’t like them — and they win — then you need to hope better qualified GOP candidates run against them next time.