Vice President Kamala Harris has razor-thin leads over former President Donald Trump in Michigan, Wisconsin and Pennsylvania, according to a new survey of the so-called “blue wall” states that could win Harris the election if she ekes out victories there.

The new Quinnipiac University poll shows Harris leading Trump in the swing states of Pennsylvania and Michigan, which are both seen as critical states for the two frontrunners. The poll comes as both campaigns court voters in swing states less than 50 days out for November’s election.