Sen. Thad CochranThad CochranOvernight Finance: GOP offers measure to repeal arbitration rule | Feds fine Exxon M for Russian sanctions violations | Senate panel sticks with 2017 funding levels for budget | Trump tax nominee advances | Trump unveils first reg agenda Senate committee ignores Trump, House budgets in favor of 2017 funding levels Overnight Finance: CBO finds 22M more uninsured under Senate health bill | GOP agrees ObamaCare taxes must go | Supreme Court to look at Dodd-Frank whistleblower protections | More tax reform hearings | Green light for partial travel ban | MORE’s (R-Miss.) primary challenger, Mississippi state Sen. Chris McDaniel, goes negative in his new ad, hammering Cochran for supporting “wasteful” spending.

“Spend 41 years in Washington, and even good men can lose touch with their conservative roots,” a narrator says in the ad. “Sadly, Thad Cochran voted for billions in wasteful spending, like the Bridge to Nowhere. He even raised his own pay eight  times.”

The ad paints McDaniel as the “conservative Republican” in the race, who fought wasteful spending as state senator and “put prayer back in schools” and will fight ObamaCare if elected.

It's McDaniel’s second ad in the race, and it’s coming just three weeks out from the primary. His first ad was a positive biographical spot that also referenced his opposition to ObamaCare and support for prayer in schools.

Cochran is considered the incumbent most vulnerable to a primary challenge this cycle, and conservative groups have rallied behind McDaniel in his opposition to the senator, but Cochran has managed to hold a solid lead in most polling of the race.