What do breasts, "mamacitas" and indecent acts with animals have in common? They’re all mudballs the campaigns of Sen. Thad Cochran and challenger Chris McDaniel are throwing at each other in hopes of gaining the edge ahead of next Tuesday’s runoff election in Mississippi.

It’s impossible to know who has the advantage at this point in the Republican primary contest. A new poll from Democratic pollster Chism Strategies shows Cochran leading 48-47 percent. Chism was one of the more accurate polls leading up to the primary on June 3. A recent poll conducted for Citizens United shows the opposite. It has McDaniel clobbering Cochran 52-40 percent.

After sleepwalking through the primary, the Cochran campaign suddenly has come alive. Cochran has been barnstorming the state with an intensity he hasn’t needed since he won what had been a solidly Democratic seat in 1978. After House Majority Leader Eric Cantor’s stunning primary defeat last week in Virginia, the Cochran campaign is, understandably, running scared.

“Well, it happens. Members of Congress – some win, some lose,” Cochran told Fox News. “It’s not an automatic proposition that you get re-elected just because you’ve done a good job.”

That is the true unknown for Cochran. How many people who think he has done a good job for the state will vote for his opponent?

Pam Ard is one of those people. A longtime supporter of Cochran, she voted for McDaniel in the primary. “I think Thad Cochran has been great for this state,” Ard told Fox News. “He has done wonderful things here, but it is time to have some new blood.”

It’s people like Ard that McDaniel is counting on to carry him to victory.

“The people of our state, they want new leadership. They want courage. They want a bold fighter,” McDaniel told Fox News. He is trying to make the case that after six terms in the Senate, Cochran has given up the fight.

“Senator Cochran has not fought the conservative fight,” McDaniel said. “He’s been silent for far too long.” McDaniel points out that the American Conservative Union rates Cochran with a D- grade during the Obama administration. Mostly, according to ACU Executive Director Dan Schneider, for his “penchant for big government.”

Mississippi has benefited tremendously from federal transfer payments. By some counts, 46 percent of the state’s revenue comes from the federal government. For every dollar Mississippi taxpayers send to Washington, the state gets three back. Cochran is campaigning on a ‘re-elect me, and the money will continue to flow' message. And he says McDaniel’s promise to reduce spending is dangerous for Mississippi.

“I think he’s an extremist,” Cochran told Fox News. “National defense, national relief to highways and roads and bridges. I served in Congress on those committees that helped direct the money to the states and he wants to zero them out.”

McDaniel acknowledges that if he has his way, Mississippians will have to make do with less largesse from the federal government. But he dismisses Cochran’s accusation of extremism.

“There is nothing extreme about wanting to balance a budget,” McDaniel told Fox News. “There is nothing radical about adherence to our Constitution. There is nothing wrong with traditional values.”

Both candidates are going flat-out to lock up every vote they can ahead of Tuesday’s showdown. McDaniel is hoping to peel off soft Cochran supporters, while the senator is reaching out to both moderate Republicans who stayed home on June 3, and Democrats who Cochran warns won’t like the outcome if McDaniel takes the seat.

So – what about the breasts, mamacitas and animals? It’s just more nastiness in what has been one of the ugliest campaigns in recent memory. The Cochran campaign is hitting McDaniel on things he said as a conservative talk radio host a decade ago, where he ridiculed a woman running for governor for using her “boobies” to get elected, and made reference to beautiful Mexican women, calling them "mamacitas."

A PAC supporting McDaniel is using Cochran’s own words against him – a rather bizarre utterance at a recent campaign appearance where he said that as a child it was fun to do “all sorts of indecent things with animals.” The radio ad from Now Or Never PAC includes a bleating sheep as the narrator says: “Tell Thad Cochran you’re no farm animal.”

All this mudslinging might seem a little beneath an intra-party contest for a seat in the venerated halls of the Senate. But a lot is at stake here. Tea Party and conservative groups who missed the boat on the Dave Brat surprise victory over Cantor are heavily invested in McDaniel. Should he pick off a heavyweight establishment incumbent, it will be their crowning achievement this primary season.