It has been a rocky few months for Christian Lindner, and for the German political system that he has thrown into chaos.

In November, Mr. Linder, who was the federal finance minister, effectively toppled Germany’s fragile government in a bid for his political life. He goaded Chancellor Olaf Scholz into expelling him from the ruling coalition.

That set off a snap election. It means that Mr. Lindner is the primary reason the country will select a new parliament on Sunday, at a time of European and global upheaval in the early weeks of the new Trump administration, and not next fall as originally scheduled.

Mr. Lindner’s move was a bid to save his party, which had slumped in the polls, from its association with an unpopular government. He was trying to avoid a temporary death sentence in federal politics. The question is whether it will work.

In the final week of the campaign, Mr. Lindner and his pro-business Free Democrats remain just under 5 percent of nationwide support in most polls. That is a crucial threshold in German politics. Score above 5 percent, and your party gets into parliament. Fall below it, and you are almost certainly out.

And yet — because of how Germany’s political system is structured — Mr. Linder retains a chance to play a kingmaker role in the formation of the next government. He just needs to scrape together a little more support, somehow.