Democratic Secretary of State Alison Lundergan Grimes, a potential challenger to U.S. Senate Republican Leader Mitch McConnell, chats with party leaders at a dinner in Louisville, Ky., on Thursday, June 6, 2013. Grimes has given no time frame announcing whether she will run in next year's election. (AP Photo/Roger Alford)
Kentucky Secretary of State Alison Lundergan Grimes (AP Photo/Roger Alford)

Update: The Grimes campaign has cancelled ad buys slated to begin next week. This post has been updated to reflect the new information.

Kentucky Secretary of State Alison Lundergan Grimes (D) on Friday abruptly cancelled reservations for television advertising it had made only yesterday.

Grimes's campaign had purchased about $37,000 in both broadcast and cable television airtime in the Louisville and Lexington markets, according to public filings made with the television stations that will run the ads. But by Friday afternoon, two Republican ad buying sources watching the market said those ad buys had been cancelled.

A Grimes spokeswoman said in an e-mail that information about the new ad would be forthcoming. She didn't immediately respond to a message seeking confirmation of the cancelled buys.

It's a crowded market even without Grimes: Senate Minority Leader Mitch McConnell (R) and businessman Matt Bevin, McConnell's challenger in this month's Republican primary, have been blasting away at each other for months. McConnell will spend at least $1.7 million on ads by the May 20 primary, while Bevin has spent about $660,000 so far on his own ads.

Republican groups have taken sides in the pricey primary battle. The Kentucky Opportunity Coalition, the Chamber of Commerce, the American Chemistry Council and Kentuckyians for Strong Leadership have spent a combined $3.5 million for McConnell. The Senate Conservatives Fund has dropped $640,000 for Bevin.

Democratic outside groups have attacked McConnell with their own spots. The Senate Majority PAC has spent $266,000 on television so far, and Patriot Majority, a "dark money" Democratic group that does not reveal its donors, has chipped in $550,000 in ads.

McConnell reported more than $10 million on hand at the end of March. But Grimes has proven an aggressive fundraiser, hauling in $2.7 million over the first quarter of the year. Grimes held $5 million in reserve at the beginning of April; both candidates are likely to advertise from the May 20 primary virtually through Election Day.