[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2010/images/04/26/art.jdobson.07c.gi.jpg caption="James Dobson Monday endorsed Kentucky Secretary of State Trey Grayson for Senate."](CNN) - The founder of the socially conservative Focus on the Family organization is weighing in on the divisive Republican Senate primary battle in Kentucky.
James Dobson Monday endorsed Kentucky Secretary of State Trey Grayson, who's fighting Rand Paul for their party's nomination.
"Trey Grayson is the only candidate with the conviction to lead on the issues that matter to Kentucky families," Dobson says in a statement released by the Grayson campaign. "His unwavering commitment to the sanctity of human life and the family resonates with me. I know that he will be a leader on these issues, not just another Senator who checks the box."
The release notes that Dobson, who no longer heads Focus on the Family, is making the endorsement as a private individual.
Grayson and Paul, a physician and the son of former GOP presidential candidate and 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. National GOP leaders rallied around Grayson at the time. But Paul, a favorite with conservatives and with many in the Tea Party movement, is running a strong campaign and has picked up a major endorsement from former Alaska Gov. Sarah Palin. Some recent polls indicate that Paul leads Grayson in the GOP primary matchup. Three other lesser known Republican candidates are also in the race.
Bunning endorsed Paul two weeks ago. Last week, former New York City mayor and 2008 GOP presidential candidate Rudy Giuliani endorsed Grayson.
Dobson's backing of Grayson follows his endorsement last week of former Sen. Dan Coats in Indiana. Coats, who is running for the GOP nomination for the right to try and reclaim his old Senate seat, is also considered the favorite of establishment Republicans in the primary battle in Indiana.
In February, Dobson backed Rick Perry in the showdown between the Texas governor and Sen. Kay Bailey Hutchison for their party's gubernatorial nomination. Perry easily won the primary election.
Kentucky's primary is May 18. State Attorney General Jack Conway and Lt. Gov. Don Mongiardo are the top two candidates battling for the Democratic Senate nomination.
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