Only about a half-dozen states were thought to be in play in the race between Biden and former President Donald Trump, but in the wake of their June 27 face-off there is some evidence that the Republican might be competitive in states that have backed Democrats in recent elections.

Minnesota, New Hampshire and Virginia are among those being closely watched. Trump’s campaign had been trying to make a play in Minnesota and Virginia—announcing plans to open offices in both states—even before Biden’s debate flop in Atlanta.

While Trump is seen as a long shot to win these states even after the debate, the idea that Biden might have to divert resources from swing states to hold the line in bluer ones is a warning sign for Democrats about his strength as the presumptive nominee.