Story highlights Race for Senate seat, already one of ugliest, has gotten nastier

Conservatives make much of Cochran's relationship with aide

Questions about challenger's relationship with picture-snapping blogger

A conservative blogger is in jail -- arrested for allegedly breaking into a Mississippi nursing home to photograph U.S. Sen. Thad Cochran 's ailing wife, who is suffering from dementia.

"It's the worst," says the narrator of a new Cochran campaign ad airing in the final stretch before the June 3 primary, not so subtly pointing the finger at his GOP Senate challenger, Chris McDaniel, trying to stir up voter disgust.

This race, one of the nastiest so far this election year, has gotten even deeper in the Mississippi mud than that.

Cochran supporters argue the reason the blogger and tea party activist took Mrs. Cochran's picture was to feed questions about the senator and his longtime aide, Kay Webber.

Conservative outlets that back McDaniel have been all over the fact Cochran rents a basement apartment in Webber's D.C. home, and that Webber has traveled extensively with Cochran on the taxpayer's dime.

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McDaniel's campaign often forwards these reports to its media email list, while the Cochran campaign calls her trips with the senator part of her job and suggestions of anything untoward are sexist.

This Republican primary was supposed to be about the big struggle of ideas within the GOP: a 36-year Senate veteran being challenged by a young tea party-backed opponent who calls the senator a big-spending, out-of-touch Republican too entrenched in Washington.

Now McDaniel is fending off questions about whether his campaign was involved in trying to photograph Cochran's sick wife.

"Our campaign had absolutely no connection to that whatsoever, and the evidence has shown that. What we're doing right now -- we're talking about the issues," McDaniel told CNN in an interview.

The next Ted Cruz?

But what gave ammunition to Cochran allies is that McDaniel's story about when he found out about the break-in has been inconsistent.

When we asked for clarification, McDaniel wouldn't go there, replying, "Look, we're going to focus on his record."

If McDaniel has his way, he would be the next Ted Cruz, going to the Senate to shake things up -- stick to conservative principles, compromise be damned.

"We don't have six more years of the status quo," he said.

"I am not going to Washington D.C. to be a member of the cocktail circuit or to make backroom deals. I'm going up there to fight and defend the Constitution. We don't have time to waste. So with all due respect I would suggest they join me in this fight because they've been silent far too long," he told us.

"He and I are very different with our ideology. He's a guy that believes in big government. He believes in big spending. He believes in increasing taxes. He believes in increasing his own pay. I am not that guy," McDaniel said.

For the tea party movement nationwide -- after a string of primary losses this election year from Kentucky to Idaho -- McDaniel has been its great hope of 2014, the candidate with the best chance of toppling an establishment Republican.

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Things were looking good for McDaniel earlier this year, especially after Cochran stumbled by telling a local reporter here that "the tea party is something I don't really know a lot about."

Millions of dollars pouring into Mississippi against Cochran come from a who's who of national tea party groups nationwide: Citizens United, Club For Growth, Senate Conservatives Fund, Tea Party Patriots and Freedomworks.

The Sunlight Foundation, a nonprofit group that tracks money in politics, says outside groups have spent $7.6 million on the race, much of it for McDaniel and against Cochran.

Fighting back against tea party challenges

But like other Republican incumbents this year, Cochran and his allies are fighting back hard.

Henry Barbour, nephew of former Mississippi governor and RNC chairman Haley Barbour, formed a super PAC called Mississippi Conservatives to help Cochran. They have been airing aggressive ads slamming McDaniel as extreme, inconsistent and out of touch with Mississippi's needs.

Other traditional GOP groups like the Chamber of Commerce have also come in with ads supporting Cochran, like they have for GOP incumbents in other states this year.

Still, Cochran's four decades in Washington have won him loyal supporters.

On Memorial Day, Cochran attended an event in Vicksburg. He was invited by the Democratic mayor, George Flaggs, who called him a "mentor" and "great friend."

Flaggs told CNN he intends to vote for Cochran in the GOP primary since Mississippi law allows Democrats and others not registered as Republicans to participate. He said Cochran fights hard for Mississippi's needs and calls his seniority -- ranking Republican on the powerful Senate Appropriations Committee, a big plus for the state.

"He's a leader; he's a statesman, and he's what we need in Washington. So stay as long as he wants to stay," Flagg said.

Republican Briggs Hopson serves with McDaniel in the Mississippi state Senate, and told CNN he likes McDaniel but that Cochran is the "best person for Mississippi right now."

"Seniority can be a plus. People can lose touch and get lazy and all those things but I don't think that's the case with Senator Cochran. He's been responsive to the needs in Mississippi for many years," Hopson told CNN.

'Those days are over'

When we put those bipartisan sentiments to McDaniel he responded with an emphatic, "come on!"

"I say name one fight Senator Cochran's lead against Barack Obama. Name one time he's raised his voice in defense of conservatism. Name one time he's fought back the liberal agenda. Name one piece of legislation he's authored in 42 years that benefited the conservative cause. Name one thing that he's been outwardly aggressive about. And they can't name one," McDaniel told CNN.

"Look, there may have been a time for that in 1973 when he first went to Washington. Maybe when Richard Nixon was president that was the thing people did. Those days are over."

We wanted to ask Cochran himself why he thinks he should get another six years, after serving 36 in the U.S. Senate and six before that in the House.

But Cochran is trying to run out the clock and avoid unforced errors -- and going to head-scratching extremes to avoid talking to reporters like us.

We tried to catch Cochran after his event in Vicksburg, but when an aide came out and saw us waiting, they did a bait and switch -- the car they told us Cochran was getting into screeched away without him, while he snuck out another door and left in another car, leaving reporters in the dust.