And down the stretch they come.
There are only six weeks until the May 20 primary between Senate Minority Leader Mitch McConnell and Republican challenger Matt Bevin.
For Team Mitch, the next few weeks are about executing the final stage of a plan that began as long ago as May 2010, when Rand Paul defeated Trey Grayson in the GOP Senate primary.
For Bevin and his out-of-state allies, the focus remains on grass-roots efforts. Russ Walker, political director for FreedomWorks, said the group had given out 20,000 yard signs, enlisted 2,000 homes and businesses as distribution centers, and given those centers 150,000 door-hangers. But, he acknowledged, "these races are tough."
With public and private polls showing Bevin continuing to trail McConnell by a wide margin, the senator's campaign is confident of victory but looking to crush Bevin as a means to test its campaign apparatus.
Josh Holmes, McConnell's senior advisor, said the campaign was taking "nothing for granted and will fight for every last vote in the primary."
"One positive development from a primary is that we have an opportunity to test some of our ground game and new technology before the general election," Holmes said. "We expect to learn a lot about various turnout models and our deployment of resources that will help a lot in November."
If Bevin has any chance of spoiling McConnell's plans, recent history suggests his move needs to happen now.
For example, it was early April when Paul broke away from Grayson in Kentucky's 2010 GOP primary for U.S. Senate. Internal polling from Paul's campaign showed the senator with a five-point lead on March 30, 2010. When the campaign got its next polling results on April 22, Paul's lead had ballooned to 13 points.
The problem for Bevin, now and throughout the campaign, is he hasn't enjoyed any of the successes Paul did.
When Paul started to move ahead of Grayson in early April, the race was a dead heat and had been for a while. More importantly, Paul raised and spent $3 million in that race. Whenever Grayson ran an ad, Paul had a response.
Bevin, in contrast, has struggled through a run of bad headlines — a letter praising the Troubled Assets Relief Program, attending a pro-cockfighting rally — and consistently has lacked the resources to introduce himself to voters or defend against attacks.
Bevin, a wealthy businessman, put more than $600,000 of his own money into the campaign when he entered the race last year. When 2014 started, he barely had more than $500,000 in cash on hand, compared to almost $11 million for McConnell.
McConnell allies, including former top aide Billy Piper, said they anticipate Bevin will make another personal loan to his campaign.
"I assume he will dig into his own fortune and hurl more dishonest nonsense aided and abetted by outside groups that don't understand or care about Kentucky voters," Piper said.
Meanwhile, FreedomWorks and other outside groups continue to push ahead with their grass-roots efforts on Bevin's behalf.
Rachel Semmel, Bevin's spokeswoman, said the campaign was "excited by the momentum the campaign has picked up."
As an example, she cited a rally sponsored by FreedomWorks last weekend in Louisville, where conservative radio host Glenn Beck was the featured speaker.
"As the thousands of grass-roots activists showed this weekend, when voters know about McConnell's 30-year record of liberal votes, they flock to Matt Bevin," Semmel said. "Kentuckians are realizing that McConnell has been too liberal for too long, and they see Matt Bevin as the conservative alternative."
Walker said the biggest challenge FreedomWorks faces during the next six weeks is introducing Bevin to voters who have never heard of him, but he said he was "cautiously optimistic."
Despite that optimism, Walker spoke of the May 20 primary in terms of moral victories, saying they "see a change in the behavior of the politician (McConnell) regardless of whether we win or lose."
Walker said he called it "the Hatch effect," explaining that Republican Sen. Orrin Hatch of Utah has voted more conservatively since a primary challenge against him in 2012.
"We force them to reconnect with their constituency on some level," Walker said. "Matt being there is the number one thing we're shooting for, but at the end of the day we've seen changes in behavior."
Rand Paul watch
Paul, who continues to lead the way-too-early race for the 2016 Republican presidential nomination, will be in the first-in-the-nation presidential primary state, New Hampshire, this weekend.
He will attend a rally Friday in Dover, held by the Granite State's Republican Party. On Saturday, he is scheduled to speak at the Citizens United and Americans for Prosperity Foundation Inaugural Freedom Summit.
Paul also is meeting with the editorial board of the Manchester Union Leader newspaper and is to tape an interview with WMUR-TV, the ABC affiliate in New Hampshire.
If you're planning to run for president, these are the kinds of things you do two years before New Hampshire votes.
James Pindell, political reporter for WMUR, said in an email Monday that Paul's "early trips to New Hampshire couldn't be much more different than his father's early trips up here."
"When Ron first visited, they were insular, intimate supporter gatherings," Pindell said. "Rand Paul's events are large-scale and often state Republican Party fundraisers where he can introduce himself — and earn chits — with a much wider audience."
Pindell said the younger Paul was "getting the respect as a real-deal, top-tier candidate."
"He is in the one-name shorthand on the tongues of politicos here," Pindell said. "(Chris) Christie, Rand, (Marco) Rubio, (Ted) Cruz and, increasingly, Jeb (Bush)."