Rep. Tom Cotton, R-Ark., will launch his bid to challenge incumbent Sen. Mark Pryor, D-Ark., next week, Cotton’s office confirmed Wednesday.

Cotton will announce his decision during a dinner in Dardanelle, Ark., on Tuesday.

“On Tuesday, Tom is inviting his hometown and all who have supported him along the way to hear about his fight to represent Arkansas’s values in D.C.,” said Caroline Rabbit, a spokesperson for Cotton. “He looks forward to sharing his plans to continue that fight in the coming year.”

Cotton has long been rumored to be weighing a bid for the Senate seat held by Pryor, a Democrat and the son of a former senator. A Republican operative confirmed earlier this year that two Democratic trackers had been following Cotton in case he decides to run.

National Democrats wasted no time attacking Cotton on Wednesday, with one spokesperson for the Democratic Senatorial Campaign Committee saying that Cotton’s decision showed “arrogance.”

“Cotton showing arrogance, poor judgement we’ve come to know from a guy who has been in House for 5 mins, reminds me of Rick Berg #ARsen,” DSCC spokesperson Justin Barasky tweeted.

Berg is a Republican who served one term in the House before running for an open Senate seat in North Dakota last year. He lost to Democrat Heidi Heitkamp.