The National Republican Senatorial Committee has bought $1.9 million worth of television in Iowa, the latest sign of a tightening race in the Hawkeye State.

The buy will begin Aug. 26 and run through Election Day on Des Moines and Cedar Rapids television, on both cable and broadcast.

Rep. Bruce BraleyBruce Lowell BraleyOPINION | Tax reform, not Trump-McConnell feuds, will make 2018 a win for GOP Ten years later, House Dems reunite and look forward Trump: Ernst wanted 'more seasoning' before entertaining VP offer MORE (D-Iowa) and Iowa state Sen. Joni Ernst (R) are locked in a close and bitter race there, a late-breaking contest that could determine Senate control.

The Democratic Senatorial Campaign Committee has already been on the air in Iowa, hitting Ernst with a $500,000 ad buy earlier this month. 

The buy is the latest sign of a shifting map for both parties. With Montana essentially off the map for both parties following Sen. John Walsh's (D-Mont.) plagiarism scandal and subsequent decision to drop his campaign this week, both Republicans and Democrats can begin to move resources elsewhere.