Prominent Republicans are redoubling their attempts to convince New Hampshire Sen. Bob Smith not to seek re-election. Rep. John Sununu, R-N.H., will announce his intention to seek Smith's seat in the last two weeks of October, Fox News has learned.

Rep. Sununu's announcement had originally been expected in August, but GOP officials said he postponed it so Smith's Senate colleagues and prominent GOP officials in New Hampshire and Washington could take another crack at convincing Smith to withdraw. Smith is considered the most vulnerable incumbent in the Senate.

And GOP efforts to recapture the majority of the U.S. Senate in 2002 have been complicated by the announced retirement plans of Sens. Phil Gramm of Texas, Jesse Helms of North Carolina, and Strom Thurmond of South Carolina.

Sen. Fred Thompson, R-Tenn., is also seriously considering retirement. These departures have strategists scrambling to shore up their chances elsewhere, starting with New Hampshire.

Smith left the GOP briefly to run as an independent in the 2000 presidential race and has often been criticized by prominent New Hampshire Republicans, even the party chairman, for various controversial positions.

The White House and the National Republican Senatorial Committee are officially helping Smith raise money, but polls show Smith would be soundly beaten by the likely Democratic nominee, New Hampshire's current Gov. Jeanne Shaheen. Those same polls indicate that Sununu could beat Shaheen.