Making official what had long been suspected, Rep. Jeff Flake (Ariz.) announced Wednesday that he would not challenge Sen. John McCain in the 2004 Republican primary and would instead seek re-election.

“After a lot of soul searching on this, I decided I’d probably get whipped,” Flake said.

McCain, whose 2000 presidential bid made him a heroic figure among unaligned voters, is seen as unassailable in an open primary format.

A lawsuit brought by the Arizona Libertarian Party that would close the party primaries is moving through the courts but is unlikely to change the state primary system before the 2004 election, regardless of the outcome.

Flake’s decision likely removes any hopes among Democrats that McCain will be vulnerable next fall. Democratic state Party Chairman Jim Pederson, who has significant personal wealth, had been mentioned as a potential candidate but has said repeatedly he would not challenge McCain. Democrats’ next opportunity will come in 2006, when Sen. Jon Kyl (R) stands for re-election.

Flake had been urged to make the race by a number of conservative interest groups, including the Club For Growth, which had contributed heavily to his 2000 open-seat Republican primary win.

His interest began to wane following the April quarterly financial reports that showed McCain had raised better than $1 million in the first three months of the year, dispelling rumors that he was contemplating retirement. Flake showed just $12,000 raised during that same time period.

Flake has pledged to serve no more than three terms, a promise that will expire in 2006 when Arizona Gov. Janet Napolitano (D) is expected to stand for re-election and Flake could be a contender for that post. But Flake refused to speculate what his political future might hold.

“I just don’t know,” he said. “It is a long time from now, and I have a lot to do in the meantime.”