All signs point to a tightening race with just three full days of campaigning to go before Election Day.

Republican nominee Donald Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE appears to have momentum on his side. But no-one knows if there is enough time left for him to fully reel in the lead held by his Democratic opponent, Hillary Clinton Hillary Diane Rodham ClintonButtigieg stands in as Pence for Harris's debate practice Senate GOP sees early Supreme Court vote as political booster shot Poll: 51 percent of voters want to abolish the electoral college MORE.

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Assuming the opinion polls are largely accurate, Clinton retains an advantage, albeit one that has been narrowed significantly.

The race could come down to a photo finish but here are several things to watch for clues as to who will ultimately emerge as the winner.

Do Trump’s numbers keep ticking up?

Late-breaking voters appear to be moving toward Trump, in both national and state polls.

Clinton does not appear to be suffering any real erosion in her support, despite negative publicity from FBI director James Comey’s announcement last week that agents were examining newly-discovered emails.

In the RealClearPolitics (RCP) national polling average, Clinton was drawing 45.1 percent support late on Friday afternoon, down only about one point from her recent high on Oct. 18. Back then, however Trump was mired at 39.1 percent, six points behind. Since then, his support has risen to 42.7 percent.

At least two factors may be working in Trump’s favor. Libertarian Party nominee Gary Johnson Gary Earl JohnsonWhat the numbers say about Trump's chances at reelection Presidential race tightens in Minnesota as Trump plows resources into state The Hill's Campaign Report: Biden condemns violence, blames Trump for fomenting it l Bitter Mass. primaries reach the end l Super PAC spending set to explode MORE has lost a couple of points in support across the same period, and it seems plausible that Trump has benefitted more than Clinton as a result. There is also polling evidence to suggest that the cohort of Republican voters that has been uneasy with Trump is finally “coming home” to him, as The Hill previously reported.

The huge question, however, is whether Trump can actually get ahead of Clinton. He has not led for any sustained period of the campaign. Is he in a real position to win the race or is he merely making it more competitive than it has been in recent weeks?

Could Clinton’s firewall crack?

Much of Clinton’s strategy has been premised on the idea that she is all-but-guaranteed to hold competitive states that 2004 Democratic nominee John Kerry John Forbes KerryThe Memo: Warning signs flash for Trump on debates Divided country, divided church TV ads favored Biden 2-1 in past month MORE carried. Among those states are Pennsylvania, Michigan, Wisconsin and New Hampshire.

That assumption has begun to look increasingly shaky in recent days. In New Hampshire, Clinton has not led in any of the four most recent major polls — two were tied and two had Trump ahead, albeit by only one or two points.

New Hampshire is the smallest of all the battlegrounds, with just four votes in the Electoral College. But Clinton is also seeing narrowing margins in Pennsylvania, where her lead is down to less than three points. Her position is better in absolute terms in Michigan, but a new poll from the Detroit Free Press released Friday afternoon had her lead down to four points from seven points a week before.

Wisconsin seems, for now, to be safer territory for Clinton. But a loss in either Pennsylvania or Michigan could complicate her White House path considerably. The two states have 20 and 16 Electoral College votes respectively,

What do the candidates’ travel plans tell us?

Clinton’s decision to go to Detroit on Friday for a get-out-the-vote event startled many observers, since it seemed to reflect concerns about the fate of Michigan and, relatedly, reports of reduced black enthusiasm.

The biggest single event of the closing stretch of Clinton’s campaign will be aimed at shoring up support in Pennsylvania — she will appear with her husband former President Bill Clinton William (Bill) Jefferson ClintonChelsea Clinton: Trump isn't building public confidence in a vaccine Hillary Clinton launching podcast this month GOP brushes back charges of hypocrisy in Supreme Court fight MORE, as well as President Obama and first lady Michelle Obama Michelle LeVaughn Robinson ObamaMichelle Obama: 'Don't listen to people who will say that somehow voting is rigged' Michelle Obama and Jennifer Lopez exchange Ginsburg memories Social media platforms put muscle into National Voter Registration Day MORE in Philadelphia on Monday evening. It is her final event before Election Day.

Trump is taking a more diverse path. On Saturday, he is in Florida, North Carolina, Nevada and Colorado. The next day sees him scheduled to hold rallies in Iowa, Wisconsin and Pennsylvania. Monday events include return trips to Florida and North Carolina, and an evening rally in New Hampshire.

Can pro-Clinton stars rock the vote?

Democrats have long held the advantage when it comes to the number of celebrities who rally to their flag. That is especially obvious in the closing days of this campaign.

On Friday evening, Jay-Z was joined by Beyoncé and several other stars at a concert at Cleveland State University intended to get out the vote for Clinton. In Philadelphia, Stevie Wonder performed at a similar event. Over the weekend, Jon Bon Jovi will pick up the baton, with events in St. Petersburg and Charlotte.

Star power is good for headlines, but will it actually make a difference at the polls?

One more surprise?

This year’s campaign has been always dramatic and sometimes downright bizarre. But could there be one more news shock, or more, still to come — either from WikiLeaks or some other source?