That's true in Arkansas as well, where Democrats are pulling out all the stops to save incumbent Sen. Mark Pryor—and, by extension, the rest of the Democratic ticket. Former President Clinton has twice headlined rallies for Pryor as well as gubernatorial candidate Mike Ross.
Still, it's been tough for those gubernatorial hopefuls to make their own mark on the airwaves when they're totally blanketed by Senate ads.
"It's been difficult [for Ross and GOP candidate Asa Hutchinson] to get traction "¦ $40 million has been spent in the Senate race, so it's really difficult for the gubernatorial candidates to be heard through that," said Jay Barth, a professor at Hendrix College who works with the college's polling outfit. (The latest Talk Business/Hendrix poll gave both Hutchinson and GOP Senate candidate Tom Cotton 8-point leads over their Democratic opponents.)
Kansas is another place where a competitive Senate race—albeit a late-breaking one—could help turn the tides. Incumbent GOP Gov. Sam Brownback looked earlier this summer to be in serious trouble, and even now is running fairly close to even in polls against Democrat Paul Davis.
But the race between GOP Sen. Pat Roberts and independent candidate Greg Orman, which heated up in late August when the Democratic candidate dropped out, brought an influx of GOP money to the airwaves, and a ground operation for the GOP that was previously almost nonexistent.
Like Colorado, the issues at stake in the gubernatorial race are far different than those in the Senate race—Brownback's weakness comes from his own handling of the state's finances, as well as his efforts to elect more conservative members of the Legislature to enact those reforms in the first place.
Still, Wint Winter, who has organized the moderate Republican revolt against Brownback, said Roberts's and Brownback's troubles feed off each other—but that there's no doubt Brownback will fare better if Roberts does, and that the Roberts campaign's ability to turn out GOP voters will play a big role in Brownback's fate as well.
"A stronger Pat Roberts, a Pat Roberts that turns out more of the conservative vote, is more helpful to Brownback than it is to Davis," he said. "A weakened Roberts, a Roberts election campaign that doesn't turn out the base, is better for Davis."
Georgia, too, could see some spillover from the Senate race to the governor's race: National Democrats recently invested an additional $1 million into the Senate race to boost Democrat Michelle Nunn, which could end up helping Democratic gubernatorial hopeful Jason Carter as well.
To be sure, there are races where a competitive Senate race has had little or no effect on the gubernatorial race. Take Michigan, for example. At first both GOP Gov. Rick Snyder and GOP Senate candidate Terri Lynn Land looked to be competitive. But Land fizzled out, falling behind by double digits in the polls and prompting national Republicans to pull ad money out of the state—and Snyder, while in a close race, still holds the lead. There's also Iowa and New Hampshire, where GOP Gov. Terry Branstad and Democratic Gov. Maggie Hassan, respectively, look poised to cruise to reelection.
But on the whole, Senate races are having a big effect on the top of the ticket this fall—and in ways that will be tough to fully understand until the results are in on Election Day.