CONWAY, Ark. — In what is likely to become a theme of the last weeks of campaigning before the midterm elections, former President Bill Clinton all but begged voters here in Arkansas not to use their vote as an expression of disapproval for Barack Obama.

The president is playing an outsized role in the race between Arkansas Democratic Sen. Mark Pryor and Republican challenger Rep. Tom Cotton, R-Ark. Obama is seriously unpopular here; a recent survey by the Democratic polling firm Public Policy Polling put his job approval rating at 31 percent, versus 62 percent disapproval.

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Given that, Cotton has relentlessly tied Pryor to Obama, saying Pryor has voted with the president "93 percent of the time" and is a reliable rubber stamp for anything Obama wants to do. The strategy has given Cotton a small but durable lead in the race; he has been ahead in eight of the last ten public surveys included in the RealClearPolitics average of polls.

Democrats are feeling the heat, and the campaign against Obama was clearly on Clinton's mind when he addressed a crowd of at least 1,000 at the University of Central Arkansas.

"[Republicans] are really running against the president, aren't they?" Clinton said. "They see the polls, the president is unpopular in Arkansas."

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"They want you to make this a protest vote," Clinton continued. "They're saying, you may like these [Democrats], but hey, you know what you've got to do. You've got to vote against the president. After all, it's your last shot."

Clinton argued that a vote for Cotton, whom he never mentioned by name, would be a vote against raising the minimum wage, against affordable interest rates for student loans, and against equal pay for women. The former president suggested that Arkansans are being seduced to vote against their own interests by anti-Obama ads paid for by out-of-state groups trying to help Cotton win.

Channeling an imaginary voter, Clinton said, "One more time, I've got to cast a protest vote. Why? Because all of this out-of-state money buying television ads tells me to. I'd like to think about Arkansas, I'd like to think about our future, I'd like to think about what would be the best for our children and grandchildren, but I just can't do it."

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Clinton's impassioned appeal was a measure of how seriously Democrats here in Arkansas, as well as in other red states, worry about Obama dragging down Pryor and other Democratic candidates.

Cotton has made enormous headway by mocking Pryor's loyalty to the president. Cotton began a stump speech in rural southeastern Arkansas Saturday, as he always does, by explaining, "Everywhere I go, I look for someone in Arkansas who agrees with Barack Obama 93 percent of the time. High and low, I look for them everywhere. I can't find them."

The Democratic effort to free Pryor and others from the weight of Obama's low ratings took an enormous hit last week when the president, rather than distancing himself from the midterms, stated boldly that they are a referendum on his policies.

"Make no mistake," Obama said during an economic speech in Evanston, Illinois. "These policies are on the ballot — every single one of them."

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Democrats across the country winced; even Obama loyalist David Axelrod declared the president's words were "a mistake." But the damage was done. Cotton and other Republicans pounced, delighted to endorse Obama's statement.

"Barack Obama said it's his policies that are on the ballot," Cotton said Saturday. "I agree for once with Barack Obama. His policies are on the ballot, as is Mark Pryor's support for them."

Democrats have good reason to worry. A president's job approval rating is a pretty reliable predictor of midterm voting, and Obama's ratings are down in several states in which Democrats are in danger of losing Senate seats. In addition to Obama's 31 percent approval in Arkansas, the president is at 39 percent in Louisiana, 40 percent in Iowa, and 42 percent in North Carolina, according to PPP.

So now Bill Clinton is leading what is, in effect, an effort to rescue the Democratic Party from Barack Obama. In Conway, Clinton pronounced himself "sick and tired of people trying to stir people up, make them foam at the mouth and vote for what they're against instead of what they're for. How many times have we seen people do something they knew better than to do just because they were in a snit?"

What Clinton calls a "snit," Republicans would call a referendum on the president — a framing that Obama himself has endorsed. Whatever the term, Clinton's visit to Arkansas was compelling evidence that Democrats are deeply, deeply worried about the shadow the Obama record has cast over November's voting.