FRANKLIN, Ky. (AP) — Kentucky Democratic Senate candidate Alison Lundergan Grimes was firing up a group of about 30 voters from a picturesque gazebo Saturday when the sun suddenly broke through the clouds and shone on her face.

"How much did she pay for that," one woman quipped as Grimes finished her speech.

It's a fair question in one of the country's most expensive and contentious Senate races. Grimes, Kentucky's secretary of state, and Republican Sen. Mitch McConnell have already raised a combined $19 million in the two years leading up to Tuesday's primary elections. But with Grimes and McConnell both holding big leads over their primary opponents, their campaigns view Tuesday as a dress rehearsal for November's showdown.

A McConnell win could help swing control of the Senate to the Republicans, setting up two years of intense fighting on the future of the nation's health care law. A Democratic win would topple a 30-year GOP incumbent and Senate leader.

About a mile from where Grimes was speaking, McConnell told a group of about 30 people at the Tanglewood Farms Market & Deli that the Kentucky Senate race was a microcosm of the national political discussion.

"We will be in the crosshairs of this great national debate about what American ought to be like," McConnell said. "Do we want to be like western European countries, with big debt, high taxes, strangulated regulations? Or do we want to be a country that's still based on opportunity and initiative and the chance to realize your dream without the government trying to micromanage every aspect of your life."

In this small Kentucky town near the Tennessee border, where registered Democrats outnumber registered Republicans by 2 to 1, Grimes and McConnell had the same message: change. Grimes would like to see Kentucky change senators, and she criticized McConnell for voting against raising the minimum wage and blocking measures to ensure women make the same salaries as men.

McConnell would like to stay in the Senate, but change jobs, from minority leader to majority leader. Republicans would have to pick up six seats for that to happen, wresting control of the Senate from Democrats. As majority leader he'd be in charge of stopping a president's agenda that he says has devastated Kentucky's coal industry and upended the country's health care system.

McConnell and his allies are already running television ads comparing Grimes to Obama, whose disapproval rating in Kentucky is at least 60 percent.

"Nothing about this election is going to change who the president is," Grimes said in an interview, calling herself a "fierce opponent" to Obama's new emission standards for coal-fired power plants, a big issue in Kentucky's coalfields. "But Kentuckians do realize that we can finally change who is in Washington, D.C."

With minimal opposition, Tuesday could likely be a victory for Grimes as she seeks to rally her base heading into November. But the primary is tricky for McConnell, who has a comfortable lead over Louisville businessman Matt Bevin but could lose some 30 percent of Republican voters to other GOP candidates. Conservatives are unhappy about McConnell's compromises with Democrats to raise the debt ceiling, pass the Wall Street bailouts and other fiscal issues.

"I think he'll have a very tough time bringing them back," said Jonathan Hurst, Grimes' campaign manager. "We will welcome those who vote against Sen. McConnell and his own party on Tuesday to join our campaign."

But Republicans in Franklin were confident that the changing political demographics of their county — with a preference for Democratic state officials and Republican federal officials — would be emblematic of the state as a whole in November.

"When I first ran for office in '98, party registration for Democrats was at that time about 5 to 1. ... It's almost dropped to 2 to 1," said Jim Henderson, a Republican and the county's top elected official. "It's because the national Democratic Party doesn't reflect even Kentucky Democrats who might consider themselves conservative."