DAVID GREENE, Host:
And people go to the polls in several states and the District of Columbia tomorrow. These are the last major primaries of the season. Among the marquis races, a special election in Delaware to fill the seat once held by Vice President Joe Biden.
Nine-term Republican Congressman Mike Castle is fighting hard for the seat, but he's locked in a fierce battle with Tea Party conservative Christine O'Donnell. Their bare-knuckled campaign is quite a departure from the traditionally civil politics of the first state, as Joel Rose reports.
JOEL ROSE: A few months ago, Delaware's Senate seat looked like an easy pickup for Republicans. The party was supposed to nominate Mike Castle, a politician who seems made for Delaware: socially moderate, fiscally conservative and almost painfully low-key.
MIKE CASTLE: How are you doing?
Unidentified Man #1: You're the man. You're looking good.
ROSE: That was Castle earlier today, shaking heads in a Wilmington park. After nine terms in the House of Representatives and two as governor of Delaware, Castle is suddenly scrambling for every vote he can get.
CASTLE: This has been a complete out-of-state operation. It's not been a local campaign. It's not had local donations. But they've spent a lot of money, and they have been on the attack hard.
ROSE: After helping to defeat incumbent Republican senators in Utah and Alaska, the Tea Party Movement set its sights on Delaware. Sarah Palin, South Carolina Senator Jim DeMint and other prominent Republicans are throwing their weight behind Christine O'Donnell, a social conservative who bears a certain resemblance to the former Alaska governor.
CHRISTINE O: We're busting up the establishment, saying voters, you decide. You decide whose message resonates with you and who you want to see represent you on the ballot.
ROSE: Delaware is a small state with the population of under a million. Politics here is usually a gentleman's game, not this year. Tom Ross is the chairman of the state Republican Party, which is backing Castle.
TOM ROSS: This is the dirtiest campaign in the history of Delaware, and they're taking a good and decent man that has served this state long and well and trying to malign him.
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Unidentified Man #2: On real issues, issues that count, Castle is just plain wrong, wrong on his votes, wrong on his record, wrong for Delaware.
ROSE: Conservatives have run ads attacking Castle for voting with Democrats, particularly on the cap-and-trade energy bill, while Castle's campaign has tried to portray O'Donnell as inexperienced and incompetent.
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Unidentified Man #3: According to the News Journal, she didn't pay thousands in income taxes, had to be sued by a university for thousands in unpaid bills, defaulted on her mortgage.
ROSE: But O'Donnell insists her opponent is making a mistake by bringing up her finances during tough economic times.
DONNELL: Yes, I've had difficulties, but what the voters seem to be looking at is that I have worked hard. I have made the sacrifices needed. And it's a shame that my opponent is trying to use that against me because it shows just how out of touch he is with those who do struggle.
ROSE: Polls show Republican voters just about evenly divided on the eve of the election. Richard Martinez(ph) of Bear, Delaware, is planning to vote for O'Donnell.
RICHARD MARTINEZ: I believe that Mike Castle in general is more in line with the progressive, liberal policies that are currently, I think, doing damage to our country.
ROSE: But Sam Starr(ph) of Newark thinks Castle gives the party the best chance to win with more moderate voters in the general election.
SAM STARR: I think he's got a better chance to win against the other Democratic opponents than she does. That's one of my main reasons for voting for Mike.
ROSE: Polls show Castle with a commanding lead over the presumptive Democratic nominee, Chris Coons, a local county executive.
CHRIS COONS: I am just preparing my family and friends for the fact that no matter who wins that primary, they're likely to go after me in the same way.
ROSE: Coons says that's not usually the way things are done in Delaware, but 2010 is shaping up as an unusual year.
For NPR News, I'm Joel Rose. Transcript provided by NPR, Copyright NPR.