Did the Tea Party movement just snatch defeat from the jaws of victory in Delaware?

In a word: Yes.

Just as wins by extreme right-wingers in Republican primaries in Nevada, Alaska and other states have renewed the hopes of Democrats in Senate races where they looked to be doomed, Delaware Republicans just ditched a seemingly certain November winner for a likely loser.   

On a night when the Tea Party movement scored some big wins over candidates of the Republican establishment—in races for governor of New York and several key congressional seats—the most dramatic victory for the frenzied right came in Delaware, where Tea Party heroine Christine O’Donnell upset Congressman Mike Castle for the party’s Senate nod.

Former White House political czar Karl Rove, who describes the Republican nominee for the US Senate from that state, Christine O’Donnell, as someone who "says a lot of nutty things," was arguing that the GOP just lost a Senate race.

"We were looking at eight to nine seats in the Senate. We’re now looking at seven to eight in my opinion," Rove said Tuesday night. "This is not a race we are going to be able to win."

But consider those numbers: What Rove is saying is that, with the Delaware result, Republicans may have lost much more than the Senate race in a single state.

Republicans currently hold 41 seats in the Senate, while Democrats have 57 seats and the support of two independents—Vermont’s Bernie Sanders and Connecticut’s Joe Lieberman.

If Republicans were to win nine seats this year, they might well convince Lieberman—or Nebraska’s Ben Nelson—to caucus with them and create a majority. If they win seven or eight, the prospect of an actual takeover becomes far less likely.

So Rove, who certainly knows his numbers, is not simply talking about Delaware when he speaks of a shift from "looking at eight or nine seats" to "looking at seven or eight." He is talking about a serious blow to the possibility that Republicans might gain control of the Senate and effective veto power over President Obama’s initiatives.

To be sure, Democrats and many independent analysts might suggest that even the "seven or eight" figure inflates Republican prospects in this year’s Senate races. But there is simply no question that the Republican narrative for the 2010 cycle was rewritten Tuesday night—not by Democrats but by Republican primary voters.

This is a turn of events that has Democrats, who have not gotten many breaks this year, celebrating. And rightly so. The thought of running against Tea Partisans—in Delaware and nationally—is far more appealing than that of competing with mainstream Republicans like Mike Castle.

That’s actually something that veteran Republicans tried to communicate to the party’s feverish wing before the primary.

The chairman of the Delaware Republican Party said that perennial candidate O’Donnell—who was plagued by reports of personal and political scandals throughout the primary campaign—was "a liar who had trouble paying her bills" who "could not be elected dog catcher."

The National Republican Senatorial Committee dismissed O’Donnell—the party’s 2008 candidate against then Senator Joe Biden—as unelectable in 2010. Committee leaders drafted Castle into the Senate race and backed him openly and aggressively as a sure bet to take the seat Biden gave up when he assumed the vice presidency.

But the best laid plans of the Republican strategists crumbled Tuesday night, when O’Donnell—who had the backing of the Tea Party Express and Sarah Palin but was condemned as corrupt by her own former campaign manager—beat Castle by a 53-47 margin.

O’Donnell thanked the Glenn Becky "9/12 Patriots" and other Tea Party groups, declaring that her run was "more of a cause than a campaign." And that will be evident as O’Donnell faces Democrat Chris Coons.

Coons, the New Castle County Executive, agreed to run as the Democratic candidate only after more prominent contenders—including Delaware Attorney General Beau Biden—skipped what looked certain to be an uphill race against Castle, a moderate who served as governor of Delaware before his election to the US House in 1992.

While Castle led Coons by a wide margin in the polls, O’Donnell trailed badly.

Those numbers caused Delaware Republican Party Chairman Tom Ross to suggest before the primary that an O’Donnell victory would be an “absolute disaster” for Republicans—and to argue that O’Donnell should not be seen as a “viable candidate for anything in the state of Delaware.”

Castle, who did not rush to endorse the woman who beat him, said before the primary: “If she’s nominated, Republicans lose the election automatically.”

That wasn’t just rhetoric.

Polls show that just 29 percent of Delaware voters have a favorable view of O’Donnell.

Polls also show that 44 percent of Castle backers say they will not vote for O’Donnell. Catle may be in that number; reports surfaced Tuesday night that he would not back his party’s nominee for the Senate.

That’s one of the reasons why Rove described O’Donnell’s win as "inexplicable".

It’s not inexplicable, however. It’s a choice. The Tea Party movement and its backers made it clear, even when they were confronted with the polls, that they cared more about nominating one of their own than nominating a viable contender going into the November. Rush Limbaugh, Sean Hannity and Sarah Palin may have thought O’Donnell was—as Hannity has said—"very substantive." But they also argued that it was necessary for her to win in order to purge RINOs ("Republicans in Name Only") like Castle from the party.

But not all Republicans agree with that strategy—or with the notion that O’Donnell is a credible contender.

"I’ve met her. I’ve got to tell you I wasn’t frankly impressed as to her abilities as a candidate," said a Republican strategist, "It does conservatives little good to support candidates who, at the end of the day, while they may be conservative in their public statements, do not evince the characteristics of rectitude and truthfulness and sincerity and character that the voters are looking for."

Which strategist?

Rove.

Say what you want about the former White House political czar.  But understand this: He is serious about winning elections. And, while Christine O’Donnell won a Tea Party primary Tuesday, she did not win Rove over.

Rove gets it. In a political year that has handed Republicans a lot of advantages, the single biggest factor keeping Democrats in the running to retain control of the Senate—and perhaps the House—is the determination of Republican primary voters to nominate Tea Party candidates who are not quite ready for the primetime of November.