The Democratic Senatorial Campaign Committee plans to go back on the air in Kentucky after the party has been encouraged by new polls suggesting the race against Senate Minority Leader Mitch McConnell is within reach.

The party committee is reserving $650,000 in airtime to boost Alison Lundergan Grimes after reviewing recent internal and public polling, a DSCC official told POLITICO. The polling, the source says, suggested that undecided voters are moving in the Democrat’s direction.

The decision comes after the big-spending party committee said last week it had no plans to up its buy on the air in Kentucky until Election Day, a sign many interpreted as meaning that Washington Democrats had given up on the race. But with the new ad buy and ongoing DSCC investment in the Grimes voter turnout effort, Democrats are signaling they believe they can still pull off an upset in one of their few pickup chances.

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Most public polls in recent weeks have shown McConnell maintaining a small but steady lead. A SurveyUSA poll this week showed the race in a dead heat, though the McConnell camp says it understates his support among men.

It’s unclear exactly how much effect $650,000 will have as the airwaves have been saturated with ads. But the move still is a risk for the DSCC given the array of seats Democrats must defend to save their endangered Senate majority.