LONDON (AP) — British political leaders rose early today to pursue undecided voters on the eve of a national election, zigzagging across the country in hopes that one last push will get the wavering to the polls.

Though opinion polls have consistently shown Prime Minister Boris Johnson’s Conservative Party in the lead, surveys suggest the margin may be narrowing before Thursday’s contest. All of the parties are nervous about the verdict of a volatile electorate weary after years of wrangling over Brexit, and increasingly willing to abandon long-held party loyalties.

All 650 seats in the House of Commons seats are up for grabs in the election, which is being held more than two years early in a bid to break the political impasse over Brexit.

Johnson has tried to focus minds on the potential of an uncertain result and a divided Parliament, which would endanger his plan to lead the U.K. out of the European Union on Jan. 31. He started his day before dawn, helping load milk and orange juice bottles onto a delivery vehicle in northern England.

“This could not be more critical, it could not be tighter — I just say to everybody the risk is very real that we could tomorrow be going into another hung parliament,” he said. “That’s more drift, more dither, more delay, more paralysis for this country.”

The main opposition Labour Party said polls showed that momentum was moving in their direction. The party has tried to shift attention from Brexit and onto its plans to reverse years of public spending cuts by the Conservatives, who have been in power since 2010.

Labour leader Jeremy Corbyn campaigned in Scotland and urged people to elect a government that would “give real hope.”