"There are those in D.C. that don't appear to be listening. There are those in D.C. that don't appear to care for the Constitution," said McDaniel in Web video. 

"We stand today ready to restore the Constitution. We stand today ready to restore this Republic. But, it will take action. It will take people across this state ready to make an aggressive move to do the right thing."

He announced his bid in his hometown of Ellisville, Miss., and sent out an email to supporters touting endorsements from nine state senators.

Cochran has not yet indicated whether he'll run for a seventh term, but he is expected to decide by the end of the year.

McDaniel will likely face difficulty picking up traction in Mississippi, as many prominent Mississippi Republicans expressed their support for the incumbent after McDaniel emerged as a possible challenger.

But within minutes of his announcement, McDaniel had already received the endorsement of three national conservative groups: the Senate Conservatives Fund (SCF), Club for Growth and the Madison Project.

Matt Hoskins, SCF executive director, praised the state senator as "a constitutional conservative who will fight to stop Obamacare, balance the budget, and get America working again" in a statement.

"Chris McDaniel is not part of the Washington establishment and he has the courage to stand up to the big spenders in both parties. He's a principled leader who will make Mississippi proud," he said.

And Club for Growth President Chris Chocola declared in the group's endorsement that "we have no doubt he’ll be a leader in the fight for economic freedom in the United States Senate.”