It’s the White House or bust for Rep. Tom Tancredo, the long-shot Republican presidential candidate who has decided to forgo a bid for re-election next year in Colorado’s 6th Congressional District.

Tancredo’s office confirmed Monday that he will retire from the House, where he made a name for himself as the most outspoken advocate of tough action to curb illegal immigration.

Tancredo, who has represented the Republican-leaning district in fast-growing suburbs west and south of Denver since 1999, had previously stated that he would reveal his intentions about the 2008 House race after baseball’s World Series, in which Denver’s Colorado Rockies participated as the National League champions. Tancredo announced his House retirement shortly after the American League champion Boston Red Sox completed a four-game sweep of the Rockies late Sunday.

The Republican Party holds a significant advantage at the outset of the open-seat race. President Bush took 60 percent of the 6th District’s votes in his 2004 re-election bid — including two-thirds of the vote in Douglas County, an area of suburbs and exurbs that has had substantial population growth in recent years. Even in the tough national political environment for Republicans in 2006, Tancredo won a fifth term with 59 percent of the vote over Democrat Bill Winter. That was just barely less than his vote share two years earlier.