This story out of Florida obviously only involves one person, and there’s no evidence that it’s part of a larger trend, but I kind of wonder why it doesn’t happen more often.

Saying the Republican Party has left her and is now owned by ideologues, former GOP state Sen. Nancy Argenziano says she will run for the U.S. House of Representatives as a Democrat.

Argenziano will seek the District 2 seat in North Florida now held by freshman Republican Steve Southerland, who unseated longtime Democrat Allen Boyd in November 2010.

In a prepared statement Monday, Argenziano likened herself to a Ronald Reagan Republican.

“The current iteration of the party abandoned real Republican principles long ago to cater to ideologues and corporations — the Koch entities, most notably — whose interests lie in the profiteering of America and the sacking of the middle class,” Argenziano, 56, wrote in a letter announcing her candidacy.

“Current Republican leaders have neither patience with nor allowance for honest elected officials, and they demand that members of the various legislatures — who, after all, have sworn to uphold the Constitution — instead just follow the hijacked party line and shut up.”

In general, when a party becomes radicalized and strays too far from a sensible American mainstream, only a couple of factors motivate the party to become less extreme. The first is losing elections. This didn’t have much of an effect on Republicans, who were beaten badly in 2006 and 2008, only to become an even more right-wing party.

The second is losing members who’ve grown disgusted by the party’s radicalism. This happened a bit over the last couple of years — Specter and Crist come to mind — but it wasn’t enough to shake up the GOP. On the contrary, it only seemed to satisfy those Republicans who want die-hard, uncompromising Republicans in their midst — and no one else.

The more Republicans say, “That’s it, the party has gone too far and I’m leaving,” the stronger the incentive the GOP will have to come to its senses.

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Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.