Mel Martinez (search), pressed by the White House to run for the Senate from Florida, said Tuesday he was resigning as secretary of President Bush's Department of Housing and Urban Development (search).

Martinez, the Cuban-born former chief executive of Florida's Orange County, has been near the bottom of polls that listed him among possible Senate contenders for the seat of retiring Democrat Bob Graham (search).

However, Bush political strategists have urged him to run, concerned that other Republican candidates might lose or create a backlash that would hurt the president's own re-election effort in 2004.

Martinez mentioned nothing about political plans in a brief statement.

"It has been a great privilege to serve the president's Cabinet and lead the 9,300 hardworking employees of HUD," Martinez said. "President Bush understands the importance of our work and the many positive ways it is transforming families and communities. Together, we have extended homeownership opportunities to more Americans and helped countless others find affordable housing in communities of their choice."

Bush wished Martinez well.

"Mel Martinez is a good friend and an exceptional public servant," the president said in a statement.

It was the third departure from Bush's Cabinet. Treasury Secretary Paul O'Neill and Christie Whitman (search), head of the Environmental Protection Agency (search), have also quit.

White House officials, at the behest of political adviser Karl Rove (search), have pushed Martinez to run for the Florida seat amid concerns among some Republicans that two other high-profile candidates, state House Speaker Johnnie Byrd and state Sen. Daniel Webster, would have trouble winning the open seat.

The White House also fears that a Senate run by Rep. Katherine Harris (search), R-Fla., a symbol of the 2000 Florida recount, would end in defeat and harm Bush's prospects in the critical electoral state.

Harris was secretary of state during Florida's recount and has signaled interest in the race. Party strategists fear her presence on the ballot could drive up Democratic turnout. However, she led among Republicans in a statewide poll earlier this month.

Martinez's resignation is to take effect at noon Friday.