But Mr. Romney’s strong debate performance last week gave him a boost, and now Republicans are eagerly awaiting the next round of Senate polls, banking that their presidential nominee’s rise will lift the rest of the party’s ticket.
“It was always going to be a close election for the [Democratic Senate] majority,” Republican strategist Ron Bonjean said. “However, the better Romney does, the better off the ground is for Republicans in these states.”
Political scientists have long debated presidential candidates’ coattails — their ability to help boost party members’ fortunes down the ticket. But there is little question that as Mr. Romney’s poll numbers dropped in September, so did support for Republican Senate candidates in swing states such as Virginia and Nevada.
In Virginia, Democrat Tim Kaine’s lead has slipped, according to the Real Clear Politics average of polls. The same has happened to Sen. Sherrod Brown, the Democratic incumbent in Ohio. In Nevada, Sen. Dean Heller, a Republican, has increased his lead over Rep. Shelley Berkley, a Democrat who is trying to unseat Mr. Heller.
Yet in Michigan, Sen. Debbie Stabenow, a Democrat, has extended her lead into double digits, and in New Mexico Rep. Martin Heinrich, also a Democrat, has built on his advantage.
“Right now these [Senate] contests are running on different tracks,” he said. “Sometimes you have [presidential and Senate races] on parallel tracks. I don’t think these are right now. But they will be to a greater extent on Election Day.”
“They’re responsible for their own campaigns. I don’t see how they can link that to Romney in September,” he said.
Likewise, Jim Manley, a Democratic strategist and longtime Senate aide who now works for public affairs firm Quinn Gillespie & Associates, said Senate candidates controlled their own destinies in September — to the benefit of his party.
“In many of the races, [Democrats] have better candidates than what we had expected,” he said.
But former Rep. Thomas M. Davis III, who represented Northern Virginia and was chairman of the National Republican Congressional Committee for two election cycles, said Mr. Romney’s September slump absolutely hurt his party’s down-ticket candidates.