It’s been almost 18 years since there was a Democrat in the Senate from Arizona. Hoping to reverse the trend in November, Richard Carmona (D) has moved himself into a close competition against Rep. Jeff Flake (R) with about four weeks left until Election Day. But he faces glaring challenges: the Republican tilt of the state, and the consistency of the GOP advantage there in recent years.

(Harry Cabluck/AP)

On paper, it would be tough to find a better recruit for Arizona than Carmona. He’s a decorated Vietnam War veteran who has also worked in law enforcement and public health. He served as surgeon general under George W. Bush, and was recruited by President Obama to join the Arizona race, lending credence to the claim that he isn’t beholden to one party all the time. And he is Hispanic, in a state with a sizable – and growing – Latino population.

Republicans have zeroed in on the Obama connection, a potentially damaging link for Carmona, with polling of Arizona showing Mitt Romney leading at the presidential level. A recent Flake ad calls Carmona “Barack Obama’s rubber stamp.”

The last time a Democratic presidential candidate carried Arizona was 1996, when Bill Clinton won reelection in a national landslide. In the three elections since, the Democratic nominee’s share of the vote has consistently hovered around 44 percent (43.9 percent in 2000, 43.8 percent in 2004, and 44.6 percent in 2008, the year home state Sen. John McCain was the Republican nominee).

Carmona has carefully toed the line in his own message, attentive to the pitfalls of doing or saying anything that would make him look too liberal. In a recent ad, he says “Republicans  and Democrats both got it wrong” on health care.

But try as he might to craft an independent image, Carmona is, at the end of the day, the Democratic nominee. In a state that leans to the right, it’s a tough label to overcome. But in recent years, Democrats have been increasingly optimistic about competing in Arizona. With Republicans adopting hard-line postures on immigration in the state (including 2010’s controversial SB 1070 measure), Democrats believe they can build increasing support among the state’s growing Hispanic population.

So they have devoted more resources and attention to Arizona. But it’s not yet clear what the net result will be. If Obama’s share of the Hispanic vote increases dramatically in Arizona this year, it would represent a departure from the consistency of the past two elections.

Exit polling data show that in 2008 and 2004, the Democratic presidential nominee received the same share of the Hispanic vote in Arizona – 56 percent. The Hispanic share of the electorate, however rose from 12 percent to 16 percent between 2004 and 2008, according to the exit poll data.

The pace at which Democrats are spending money underscores their seriousness about competing in the Arizona Senate race. The Democratic Senatorial Campaign Committee recently released an ad casting Flake’s record on women’s issues in an unflattering light and has committed more than $1 million to the airwaves in addition to the $500,000 in coordinated money it has spent with Carmona’s campaign.

Flake faced a Republican primary that cost him more than what was reflected in the Election Day vote tally. He ran against Wil Cardon, a self-funder who proved to be no match at the polls in late August. But Cardon’s wealth forced Flake to keep pace by burning though his own campaign cash at a faster-than-ideal pace. Democrats took advantage, swamping the airwaves during the three weeks after the primary election.

Meanwhile, Flake and his allies have sought to take some of the sheen off of Carmona’s profile. The National Republican Senatorial Committee is spending $573,000 on a buy this week, and the anti-tax Club for Growth has already been on the air attacking Carmona.

For his part, the congressman who has crafted a reputation as a strict fiscal conservative in the House used a recent ad to point out a debt increase during Carmona's tenure at the helm of the Pima Country health system. And reports about Carmona’s former boss criticizing his temperament could surface as an issue during the stretch run.

Both sides are aware of the importance of Thursday, when early voting kicks off, in the midst of a period when polling shows a very close race. Early voting is very popular in Arizona, and a good ground organization is the key to campaigns that capitalize on its appeal. Carmona is enlisting the help of former president Bill Clinton at a get-out-the-vote rally Wednesday.

Democrats deserve credit for expanding the Senate map and competing in Arizona. But the fundamentals of the state still favor the GOP. That may ultimately mean that Democrats have to wait until a future election before they can claim an unlikely statewide victory in the Southwest.