Freshman Rep. Tom Cotton (R-Ark.), as expected, announced his campaign for Senate on Tuesday, giving the GOP a top recruit against Sen. Mark Pryor (D-Ark.).

"I joined the Army to serve our country and to defend our freedom overseas," Cotton said in a statement. "That’s why I ran for Congress last year — to serve you and to defend our freedom in Washington — and that’s why today I’m announcing my candidacy to be your United States senator."

Cotton's announcement has been expected since last week, when it was reported that he will challenge Pryor, who is arguably the GOP's top incumbent target in 2014.

Cotton, a war veteran, said his conservative state needs someone who will stand up to President Obama.

"Arkansans need a senator who won’t just stand by and accept the status quo," he said. "I will be that senator."

Earlier Tuesday, Pryor's campaign launched a preemptive ad buy against Cotton, criticizing him for running for Senate so soon after being sworn into Congress for the first time. (Cotton won his first term in November.)