Nevada, North Carolina and Florida could all be decided before Election Day because of historic spikes in early voting, Clinton campaign manager Robby Mook said Thursday.

“We are encouraging supporters to cast their vote early because it is possible … that we could build an insurmountable lead in those key states before Election Day,” Mook said on a press call with reporters.

Wins in those three states would make it very difficult to imagine an Electoral College scenario in which Trump, the Republican nominee, would win the White House.

Victories in North Carolina, which Republican Mitt Romney won in 2012, and Florida are especially important.

Mook estimated that 40 percent of votes in those battleground states could be cast before Election Day.