HELENA — U.S. Sen. Jon Tester is spending the weekend before the election barnstorming the state with other Democrats in a final effort to break through a tough-as-nails battle with U.S. Rep. Denny Rehberg.

Rehberg had a quieter weekend, spending his time with family and at his Billings field office helping volunteers make calls encouraging voters to the polls.

 AP Photo/Matt Gouras

Rep. Denny Rehberg, R-Mont., right, campaigns with Sen. John Thune, R-Mont., left, in Helena on Oct. 16. Rehberg has been turning to out-of-state surrogates to help him rally his base in the election’s closing days, while incumbent Sen. Jon Tester, D-Mont., is relying on his own star power to excite his followers.

Tester spoke to well more than a hundred highly energized Democrats at a Helena Sunday rally for all the party's statewide candidates. Tester urged them to get all their friends and family to the polls. He said protecting Medicare, Social Security, and aid to college students all hang in the balance.

Tester said he wants voters who go to the polls on Tuesday to consider which candidate has done more for the state. He argues that while he has been working on issues ranging from VA facilities to health care access, Rehberg has been doing little other than "just talk about it."

"They have done their level best to make me something I am not," Tester said of the political attacks that have dominated the most expensive race in state history. "I think Montanans are smart enough to know its garbage. I hope they just think about what I am, and the kind of person I am."

Rehberg on the other hand, didn't announce any public events for the weekend. The Republican said he was in his Billings field office helping volunteers make phone calls and spending some time with family. Rehberg said he decided against a "20th century-era" statewide tour to close the election because so many people now vote early.

As he joins the phone bank, Rehberg's closing message to voters remains the same as when his campaign began nearly two years ago: This election is a referendum on President Barack Obama.

"I think Obamacare is a mistake, and I think the people of Montana agree with me," Rehberg said in a phone interview.

In a last-ditch strategy to help Tester, at least one group sympathetic to the Democrat has been spending a significant amount of money trying to attack Rehberg's perceived weakness on his conservative flank. Fliers have been filling mailboxes, and along with advertisements on the Internet and television, they argue the right choice for those worried about federal government intrusions is Libertarian Dan Cox.

Cox, who is running a threadbare campaign, is welcoming the unexpected support. And many Democrats think Cox needs to win at least a few percentage points if Tester is going to come out on top in a squeaker. Cox only received 1 percent in a Mason-Dixon poll released Sunday morning, while Rehberg was favored 49-45.

The Republican party cried foul late in the week — pointing out some of the filers were sent out anonymously and don't say who was actually paying for them.

Rehberg said voters opposed to Obama know that he is the candidate best placed to get elected and roll back the Democrat's policies.

"Frankly, Jon Tester needs the support and his people know it," Rehberg said of the push for Cox. "I don't think the people of Montana will be fooled."

Rehberg rolled out a last-minute endorsement on Saturday that could help shore up the Libertarian-minded portion of his base. The endorsement from U.S. Sen. Rand Paul of Kentucky was clearly meant to remind those voters that Congressman Ron Paul also has supported Rehberg's run.

"Denny Rehberg will vote to audit the fed," Rand Paul wrote.

Rehberg has also recently uncorked a testimonial television advertisement from Mitt Romney, who is expected to top President Barack Obama by a large margin in the state. Tester has to convince many of those Romney voters to turnaround and vote for a Democrat in the very next race on the ballot.

Tester spent the final weekend on a blitz through Kalispell, Missoula, Butte, Helena, Bozeman and Billings before planning to finish in Great Falls on Monday.

"I expect to win. But we could lose," Tester said. "It will all be on voter turnout."