(CNN) – Kentucky Secretary of State Trey Grayson is touting a high profile endorsement in his bid for his state's Republican Senate nomination in a new campaign commercial. Grayson was officially endorsed Tuesday by Senate Minority Leader Mitch McConnell, who is also the state's senior senator. Grayson and Rand Paul are the top GOP contenders in the battle for the GOP nomination. Kentucky holds its primary in two weeks.
"Trey Grayson has a proven conservative record as Secretary of State, cutting his office budget by 15% and ensuring that Kentucky's taxpaying families have easy access to information about his office and budget," says McConnell in a statement released by the Grayson campaign.
"I rarely endorse in primaries but these are critical times. President Obama's spending threatens to destroy more jobs. I know Trey Grayson and trust him. We need Trey's conservative leadership to help turn back the Obama agenda," says McConnell, in the new ad.
The Grayson campaign tells CNN that the commerical will run on broadcast and cable across Kentucky, and that the ad buy is the largest of their campaign to date.
Reacting to the McConnell endorsement and commercial, Paul campaign manager David Adams tells CNN that Paul "is right on the issues Kentucky voters care about, and he has earned the credibility he needs to win this race on May 18."
Grayson and Paul, a physician and the son of Texas Rep. Ron Paul, are running to succeed Sen. Jim Bunning, the Republican lawmaker who announced last summer that he would not run for a third term. Some national GOP leaders rallied around Grayson at the time.
The McConnell endorsement is the latest in a series of high-profile officials who have gotten involved in the primary. Paul, a favorite with conservatives and with many in the Tea Party movement, picked up a major endorsement from former Alaska Gov. Sarah Palin. Most recent polls indicate that Paul leads Grayson in the GOP primary matchup. Three other lesser-known Republican candidates are also in the race.
Last month, Bunning endorsed Paul and former New York City mayor and 2008 GOP presidential candidate Rudy Giuliani endorsed Grayson. The Grayson campaign announced Monday that Rep. Hal Rogers, who has represented southeast Kentucky for 30 years, backed Grayson. The district could be instrumental in the outcome of the May 18 primary.
Also Monday, James Dobson, the founder and former head of the influential socially conservative organization Focus on the Family, endorsed Rand Paul after originally backing Kentucky Secretary of State Trey Grayson last week.
Kentucky Attorney General Jack Conway and Lt. Gov. Don Mongiardo are the top two candidates battling for the Democratic Senate nomination.
Follow Paul Steinhauser on Twitter: @psteinhausercnn