Rand Paul as kingmaker in US Senate race in Montana?

Sen. Rand Paul (R) – heir to his father's libertarian political dynasty – on Sunday endorsed Republican Denny Rehberg, who is running in a tight three-man race. A GOP concern is that the Constitution Party candidate could siphon votes from Rehberg. 

Could Sen. Rand Paul (R) of Kentucky make the difference in the squeaky-tight US Senate race in Montana?

Senator Paul, heir to the libertarian political dynasty built by his father,  Ron Paul, endorsed the Republican Senate candidate in the Big Sky State, Rep. Denny Rehberg (R), on Sunday. The Ron Paul-lead Liberty PAC had previously endorsed Representative Rehberg.

“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 [majority leader] Harry Reid and his liberal allies in control of the U.S. Senate,” Rand Paul said in a recorded message distributed by the Rehberg campaign.

That "anyone other than" Rehberg is not just a reference to Democratic incumbent Sen. Jon Tester. It also refers to third-party candidate Dan Cox, who is carrying the libertarian banner in the election and who could siphon enough votes from Rehberg to hand the race to Senator Tester. 

The libertarian party’s presidential nominee, former New Mexico Gov. Gary Johnson, has endorsed Mr. Cox. Cox, who runs an online fishing supplies company, is formally running as the Constitution Party candidate.

Tester, a farmer from Big Sandy, Mont., won his seat in 2006 by the fewest votes of any US Senate race that year. The 2012 contest looks to be just as close.

The Rand “endorsement indicates more that the Rehberg folks take locking down that vote seriously than anything else,” wrote David Parker, a professor at Montana State University who is writing a book about the race, in an e-mail to the Monitor. “Will it matter? Hard to say.”

The Tester campaign believes Cox could be a secret weapon. An anti-Rehberg group, Montana Hunters and Anglers Leadership Fund, recently put $500,000 behind an advertisement touting Cox as the “real conservative” in the race. 

The Montana Republican Party, for its part, has filed a Federal Elections Commission complaint alleging that environmental groups backing Tester did not properly disclose their funding of a pro-Cox piece of political mail. 

The race has been a nip-and-tuck contest all the way through. Rehberg holds a 49 percent to 45 percent edge over Tester in a Mason-Dixon poll released Sunday, just within the poll’s margin of error of 4 percentage points. Cox took 1 percent, and undecided voters clocked in at 5 percent. A Public Policy Polling survey released Sunday night showed Tester with a two-point advantage.

The Real Clear Politics rolling average of polls, however, shows Rehberg with a miniscule edge of 0.4 percentage point.