Democrats love a good fight on the right.

And that’s what they’ve been getting in Delaware, where voters head to the polls Tuesday to vote in the GOP primary battle between Christine O’Donnell and Rep. Mike Castle for the U.S Senate.

National Democrats have gleefully passed along news to reporters showing the insurgent O’Donnell picking up steam against Castle, a moderate Republican. The thinking goes that Tea Party-backed Republicans bode well for them, as they will be easy to paint as extreme and out of touch with mainstream voters.

And there’s been a lot of news to pass on. In Delaware, the nasty Republican primary has largely pitted the national Tea Party Express — who has devoted its resources to helping O’Donnell stage an upset against Castle — against the GOP establishment in Delaware, which supports Castle.

Here’s a glimpse of how the race has been: The Tea Party Express on Monday called on a top Castle surrogate, Delaware Republican Party Chairman Tom Ross, to resign his state party position and run for “dog catcher,” a “job that is more suited to his talents.” The Tea Party Express made the statement in response to a PPP poll released Monday showing O’Donnell leading Castle 47 percent to 44 percent. Ross once suggested O’Donnell had a better chance of being elected “dog catcher” than U.S. Senator.

But even within the Tea Party movement, not all are backing O’Donnell. Former Republican Majority Leader Dick Armey’s FreedomWorks — an organization involved in the Tea Party movement that has endorsed a number of conservative candidates this cycle — suggested Monday that they aren’t endorsing O’Donnell because they’re not confident she can beat the Democratic nominee in November.

And as columnist Matt Lewis points out, conservative writers are also duking it out over the race. “While other primaries have exposed cleavages between establishment Republicans and conservatives, the O’Donnell campaign has driven a wedge between bona fide conservatives,” wrote Matt Lewis at Politics Daily.

Lewis argues that conservatives are attacking fellow conservatives by “utilizing the very tactics of the left.” One example he notes is how — in response to an eyebrow raising story about O’Donnell suing the conservative Intercollegiate Studies Institute over gender bias — conservative blogger Dan Riehl called ISI President Ken Cribb “a Beltway welfare queen” because Cribb makes $600,000 a year. That sort of class warfare argument, Lewis suggests, seems more like a Democratic attack line.

But the Democrat love affair with O’Donnell isn’t likely to last much longer. Even as national Democrats highlight the reports about her picking up endorsements from Sarah Palin and Jim DeMint, they are likely readying to turn around and paint her as extreme if she wins the nomination.

NEXT: We’ve seen this before in Nevada
We’ve seen it before in numerous GOP primaries. In Nevada’s Senate race, for example, national Democrats — and Senate majority leader Harry Reid — relentlessly attacked the more moderate GOP candidate in hopes that it would help Sharron Angle win the Republican nomination. When Angle won, Democrats unleashed an all out assault on her for being outside the mainstream.

Still, the Democrats see the contentious inter-party battle in Delaware as a positive for them regardless of who wins.

“Christine O’Donnell is raising the same concerns about Mike Castle that Democrats will raise in November — he is a hypocritical, entrenched politician who helped to bring our economy to its knees,” said Deirdre Murphy, national press secretary for the Democratic Senatorial Campaign Committee.

A spokesman for the National Republican Senatorial Committee didn’t respond to a request for comment.