Indeed, Democrats — aware of Rove's reputation for pulling out all the stops when necessary and his ability to call on a shadow political machine of interest groups and donors to attack opponents — said they remained worried about what kind of effort Rove might unleash in the closing weeks of the campaign.

Rove's associates say he appreciates the need of candidates to distance themselves from the White House to win. But he was described as angered by candidates who he thought were going too far in criticizing Bush out of concern that attacks could further damage an already weakened president, they said.

And the limits of Rove's influence were made clear this year when he was unable to convince the speaker of the Florida House of Representatives, Allan G. Bense, to run in the Republican primary for Senate against Rep. Katherine Harris, whom the party judged to be a weak candidate. Rove invited Bense for a sit-down at his vacation home in Rosemary Beach, Fla., as part of a long but failed effort to get him to challenge Harris for the nomination, said Towson Fraser, a spokesman for Bense.

Rove meets in person only infrequently with the Republican leaders of the Senate and House campaign committees, Sen. Elizabeth Dole of North Carolina and Rep. Thomas M. Reynolds of New York, though Dole said he was always ready to jump on a plane to a fundraiser at her request.

Reynolds said the White House had been untiring in raising money and providing surrogates. But he made clear that when it came to the House races, he was running the show.

"I'm the one who put together what I think is our best effort to win a House majority in 2006," Reynolds said.

In the Ohio Senate race, Rove has found himself in a back-and-forth with Sen. Mike DeWine. DeWine has at times resisted Rove's counsel that he employ an unrelenting focus on terrorism, exhibiting what other Republicans described as ambivalence about a television commercial depicting the World Trade Center burning.

Candidates and strategists across the country say that that they hear from Rove infrequently.

Gov. Mitt Romney of Massachusetts, chairman of the Republican Governors Association, said he encountered Rove at a dinner at Vice President Dick Cheney's home here in late July. "We chatted for a minute," Romney said. "He was interested in how the governors' races were looking. But it was interest as a fellow Republican."