With his poll numbers lagging and Election Day less than two weeks away, President Donald Trump may need to make a compelling case for reelection Thursday in the final presidential debate. Over 35 million Americans have already voted in the presidential election but Trump may seek to sway some undecided voters and boost conservative turnout by outshining Democratic nominee Joe Biden.

Every general election poll since mid-September shows Biden with the advantage and with a double-digit lead in some surveys. Adding to Trump's woes are polls showing he trails in key swing states Michigan, Pennsylvania and Wisconsin. Meanwhile, two major swing states — Florida and Ohio — appear to be a toss-up, while some red-leaning states — Arizona, Georgia and Iowa — have shown Biden leading.

The debate may need to be a "game-changer" for Trump to keep his campaign alive, as he continues to struggle with several key voting groups. Many believe Trump, who has not polled well with women and college-educated voters, will need to find ways to broaden support outside his base.

“It’s his only chance,” former Republican New Hampshire Sen. Judd Gregg told USA Today. “You don’t win elections with 30 to 35% of the vote.”

Trump did little to help his cause after the first debate on Sept. 29. According to a CNBC/Change Research poll conducted days after the debate, 53% of likely voters nationwide said Biden did a better job in the debate, compared to Trump's 29%. Even Trump's debate coach, Chris Christie, was critical of Trump's performance.

However, it's unclear how much of a boost Trump can get on Thursday night. The CNBC/Change Research poll showed that just 2% of respondents said the first debate changed their vote -- a low percentage and one that will carry less significance given that so many Americans have already voted.

Meanwhile, Biden may need a strong performance, as well. According to Biden's campaign manager Jen O'Malley Dillon, there are fears that Democrats may be suffering from complacency.

“The reality is that this race is far closer than some of the punditry we’re seeing on Twitter and on TV would suggest,” O’Malley Dillon noted in a recent memo. “If we learned anything from 2016, it’s that we cannot underestimate Donald Trump or his ability to claw his way back into contention in the final days of a campaign, through whatever smears or underhanded tactics he has at his disposal.”