Democratic presidential nominee Hillary Clinton. Justin Sullivan/Getty Images Renowned statistician Nate Silver warned Friday that new polling could indicate trouble for Hillary Clinton as the 2016 race for the White House enters its final days.

“There’s been a potential breach of Hillary Clinton’s electoral firewall,” Silver wrote on his data-journalism publication, FiveThirtyEight.

Silver was referring to the so-called blue wall — states that have reliably voted for Democrats in the past several election cycles — and other states which have solidly been in Clinton’s court throughout the cycle.

Specifically, Silver pointed to New Hampshire where polls have increasingly narrowed. Three polls released on Thursday showed Donald Trump at least tied with Clinton in the Granite State.

“If Clinton lost New Hampshire but won her other firewall states, each candidate would finish with 269 electoral votes, taking the election to the House of Representatives,” he noted.

Silver added that if Trump managed to win the 2nd Congressional District in Maine, the Republican presidential nominee would emerge as the winner of the Electoral College, 270-268.

The statistician also highlighted the tightening of polls in Michigan and Pennsylvania. A Friday Michigan poll, for instance, conducted by a Republican research firm, found Trump and Clinton tied at 44%, and other polls have shown a closer race there in recent days.

Those polls jived with other national and battleground polls that have been released over the past week. Clinton’s strong lead slipped after the FBI announced that it had reactivated its investigation into her private email server.

Election Day is on Tuesday. FiveThirtyEight's "polls-plus" forecast Friday gave Clinton about a 65% chance of winning: