On the day that Michele Bachmann officially backed former rival Mitt Romney for the Republican president nomination, Rick Santorum announced an endorsement of his own -- in the GOP primary for Nebraska's Senate race.

While Santorum passed on endorsing Romney, now the presumptive Republican nominee, he had high praise for the conservative credentials of Nebraska Attorney General Jon Bruning, the leading candidate in the GOP primary.

"Jon Bruning is a trusted conservative who is unapologetically pro-life, will fight to reduce the size of the federal government and will ensure that the government spends less and does not tax more. And there is no question that Jon is the strongest conservative candidate to defeat Bob Kerrey in November and help Republicans take back the Senate," Santorum said in a statement on Thursday.

In the most recent polling in the race, released in late March, Bruning led the Republican field with a 17-point edge over Kerrey. Polling firm PPP declared at the time that "Jon Bruning's chances of being Nebraska's next Senator are looking pretty darn good," a statement with which Santorum clearly agreed.

"As Attorney General, Jon Bruning is leading the fight in Nebraska against Obamacare, and I know he will use that same courageous spirit to repeal Obamacare in the halls of the U.S. Senate. We need to elect as many conservatives as possible this November who believe as strongly as Jon does that forcing Americans to buy health insurance is unconstitutional," his statement said.

The praise for Bruning on health care contrasts sharply with Santorum's attacks on Romney over the same issue. During his campaign for president, Santorum called Romney "uniquely unqualified" and "the worst Republican in the country" to challenge Obama on health care because of Romney's record as the governor of Massachusetts.

Bruning earned headlines in March for publicly criticizing Nebraska State Treasurer Don Stenberg, a primary opponent, for following his 14-year-old daughter on Twitter.

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