LITTLE ROCK, Ark. — A political action committee on Wednesday announced a new television ad airing around Arkansas targeting Republican Senate hopeful Tom Cotton on Medicare and the Farm Bill, two issues that Democrats believe will be key in U.S. Sen. Mark Pryor's fight for a third term.

Patriot Majority USA announced it was spending about $300,000 on the ad airing statewide criticizing Cotton, a congressman representing south Arkansas. Cotton announced in August he would challenge Pryor, a Democrat who was first elected in 2002 and won re-election in 2008.

"We're Arkansas. In tough times we stand together. But not Congressman Tom Cotton," the narrator says in the ad.

The spot criticizes Cotton for being the only member of the state's congressional delegation to vote against the Farm Bill last month. Cotton last month said he opposed the measure because he believed it didn't cut enough from food stamps and didn't do enough for the state's farmers.

The spot also criticizes Cotton for supporting the budget plan last by Budget Committee Chairman and former vice presidential nominee Paul Ryan, which called for gradually raising the Medicare eligibility age for future beneficiaries.

Cotton's campaign derided the ad, saying the Ryan plan would not affect those currently on Medicare or nearing retirement.

"(Senate Majority Leader) Harry Reid and Senator Pryor are trying to mislead and scare Arkansas seniors with their Washington-style attack ads," spokesman David Ray said in an email.

Both issues are expected to play heavily in the re-election fight for Pryor, widely viewed by Republicans as the most vulnerable incumbent in the Senate. Pryor earlier this month began airing TV spots criticizing Cotton for supporting the Ryan plan, and he's been targeting his Republican rival for the Farm Bill vote.

The race is expected to be one of the most expensive in the county, with the two rivals and outside groups already blanketing state TV stations with ads. The Center for Responsive Politics says the two candidates and outside groups have spent more than $7.4 million on the race so far.