Arkansas Rep. Tom Cotton’s Senate campaign is pushing back on recent polls showing the Republican trailing Democratic Sen. Mark Pryor.  

In an internal poll conducted for Cotton by OnMessage Inc., Cotton and Pryor are in a dead heat. It found the freshman lawmaker taking 42 percent of the vote to Pryor’s 40 percent, with 12 percent undecided. The Cotton poll comes after an NBC/Marist poll released Monday found Pryor with an 11-point lead over Cotton, with 51 percent of voters supporting him. A New York Times/Kaiser Family Foundation poll released last month also had Pryor leading by a wide margin, 46 percent to 36 percent.  

In the Cotton polling memo, pollster Wes Anderson criticized the NBC/Marist poll for sampling registered voters instead of likely voters and for under-sampling Republicans.  

The internal poll surveyed 600 likely voters statewide from May 6 through May 8. Thirty-six percent of respondents were Republicans, 36 percent were Democrats and 26 percent were independents. It had a 4-point margin of error.  

Pryor is considered one of the most vulnerable incumbents this cycle, but the race is expected to remain close heading into the fall. The race is rated Tilts Republican by the Rothenberg Political Report/Roll Call.