In the final weeks of a cross-country battle for Senate control, officials in both political parties are making multimillion-dollar advertising decisions that offer clues about where the real battlefields lie.

In Kentucky, after spending about $2 million to attack Republican Sen. Mitch McConnell, the Democratic Senatorial Campaign Committee went off the air Tuesday. The decision was a sharp blow to Democrat Alison Lundergan Grimes, and came one day after the two candidates met in their only televised debate of the campaign. The committee is continuing to fund get-out-the-vote operations.

At the same time, Democrats chose to put nearly $1 million behind Michelle Nunn, challenging for a Georgia seat now in Republican hands. Last week, Democrats put South Dakota on the board by investing in Rick Wieland’s campaign against former GOP Gov. Mike Rounds.

Republicans are flooding Kansas with campaign help for Sen. Pat Roberts, who’s in a tough re-election fight against independent candidate Greg Orman. The Kansas effort is part of their national drive to gain the six seats required to control the Senate.

There also are highly competitive races in Alaska, Arkansas, Colorado, Iowa, Louisiana, New Hampshire and North Carolina.

The Democratic Party ads in Kentucky went off the air as scheduled after Monday, at the end of a two-week period. That does not mean they won’t go back on the air before the election. But the party made no commitment to resume them.

Grimes sounded defiant while campaigning in northern Kentucky on Tuesday.

“He can buy the airwaves, but he can’t buy the hearts and minds of Kentuckians,” she said of McConnell.

Grimes’ campaign continues to air ads, including one that accuses McConnell of supporting amnesty for 3 million immigrants living in the country illegally. MoveOn.org, a liberal political action committee, has called on the Democrat to pull the ad because it refers to immigrants as “illegal aliens.”

Grimes was heavily recruited by Democrats to challenge McConnell, but her support has slipped a bit in recent polls under the weight of attacks by the five-term Senate Republican and his allies.

While McConnell has been plagued by low approval ratings, he has sought to turn the election into a referendum on President Barack Obama, who is even more unpopular in the state.

In recent days, the issue of Obama moved to the top of the daily campaign back-and-forth, with Grimes refusing to say if she voted for the president in 2008 or 2012, even though she was a delegate for the president at the Democratic National Convention in 2012.

Grimes has proven to be a formidable fundraiser, besting McConnell by nearly $1 million in the second fundraising quarter. Her campaign announced Tuesday it had raised $4.9 million in the quarter ending Sept. 30, breaking her own state fundraising record. The campaign says it has $4.4 million in cash available to spend, more than any Democrat in a competitive U.S. Senate race.

Despite that, Grimes’ campaign has been outspent by McConnell and his network of super PACs by tens of millions of dollars.

The United Mineworkers of America, which endorsed Grimes over McConnell, started running $318,000 worth of TV ads attacking McConnell in the Evansville, Indiana, and Charleston, West Virginia, markets that cover much of Kentucky’s coal fields.

But on the same day, the Kentucky Opportunity Coalition, the super PAC supporting McConnell, launched yet another $1.2 million TV ad buy that again connects Grimes to Obama.

Republicans who track the race also said Grimes is no longer benefiting from ads from the Senate Majority PAC, an independent group that is allied with Senate Majority Leader Harry Reid and has spent millions on competitive races. A spokesman for the group did not respond to requests for comment.