Montana Republican Rep. Denny Rehberg earned the endorsement of Sen. Rand Paul on Saturday in his race to unseat Democratic Sen. Jon Tester.

Rehberg had previously received the endorsement of Paul’s father, Texas Republican Rep. Ron Paul.

“America is at a crossroads. Every day the federal government grows bigger, taxing more, spending more, eroding our personal freedoms and liberties. We can take our country back, but Senate Majority Leader Harry Reid stands in our way,”Paul said on Saturday. “That’s why I, along with my father, Ron Paul, have endorsed Denny Rehberg for Senate — because we know that if you help Denny defeat liberal Senator Jon Tester, Harry Reid and his liberal allies will no longer control the Senate.”

“Denny Rehberg will vote to audit the Fed. Denny Rehberg will help me eliminate wasteful foreign aid spending, repeal Obamacare and prevent trillion-dollar deficits. … I support Denny Rehberg and encourage you to do the same, because a vote for anyone other than Denny Rehberg is a vote to keep Harry Reid and his liberal allies in control of the U.S. Senate.”

The line “anyone other than Denny Rehberg” refers not just to Tester, but also to Libertarian candidate Dan Cox, who might play the role of spoiler. Rehberg and Tester are locked in a virtual tie, and if Cox pulls enough of the vote away from Rehberg, Tester could emerge victorious.

One Democratic group has been sending out mailers and running an ad telling Montanans to vote for Cox, in what appears to be an attempt to help Cox pull votes from Rehberg.

The endorsement from Ron Paul, who is considered something of a figurehead for the libertarian movement, and his son Rand could be crucial for Rehberg, helping to pull libertarian voters who might vote for Cox into the Rehberg tent.

“It is unfortunate if they actually did endorse Denny Rehberg, since he’s rarely followed the constitution,” said Cox, who initially questioned the veracity of the reported endorsements.

“I don’t think it really plays well for Denny Rehberg because the main stream Republican party has given Ron Paul such a bad name that I don’t know why he’d want to be attached to that,” Cox went on, calling Rehberg a “main stream Republican.”

The Pauls’ endorsements might “make the Mitt Romney style voters angry,” Cox said, but it would also “anger a lot of the Ron Paul voters who know that Denny Rehberg doesn’t deserve the endorsement.”

“I’m honored to have the endorsement of Ron and Rand Paul,” said Rehberg. “Dr. Paul and I have long worked together on ‘Audit the Fed’ legislation, which we were able to pass through the House this year, and I look forward to working with Rand in the Senate to advance a pro-growth, pro-liberty agenda that will get our country back on track.”

The audio of Sen. Paul’s endorsement will run as part of “live dials” in Montana — a state where robo-calls are illegal, according to a person familiar with the Rehberg campaign.

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