Former Vice President Joe Biden’s consistent polling lead over President Donald Trump is showing signs of narrowing in key swing states on the eve of the election.Biden still holds a strong advantage in most national surveys of voters, and appears poised to maintain that sizeable polling lead rolling into Election Day. But the race is much tighter in a handful of battleground states that play a central role in the Electoral College, which will ultimately decide the winner.Here’s what national polling trackers said Monday afternoon:Despite the slightly tightening averages of national polls, Biden is still well ahead of where then-nominee Hillary Clinton stood against Trump in the final days of the 2016 election. Clinton won the popular vote in that race, but narrow defeats in key states ultimately cost her the White House.Some of those same states show Trump and Biden neck and neck, according to polling averages.RCP’s average of polls in six key battlegrounds — Florida, North Carolina, Pennsylvania, Michigan, Wisconsin and Arizona — has Biden leading Trump by 2.7 percentage points. Trump won all of those states in 2016.North Carolina and Arizona, both of which have voted for the GOP’s presidential candidates in most modern elections, are the tightest races in that polling tracker.The most recent NBC News/Marist poll of Arizona, released Monday afternoon, showed Biden and Trump in a dead heat. Both candidates had the support of 48% of likely voters, according to that poll, which has a margin of error of plus or minus 4.5%.But that pollster also found Biden up 5 percentage points in Pennsylvania, which has 20 electoral votes up for grabs and is considered by some analysts to be the most important state in the election. Biden had the support of 51% of likely voters in Pennsylvania, compared with 46% for Trump, according to that poll, which had a 4.4% margin of error.RCP’s polling average had Biden up 2.9 points on Trump in Pennsylvania on Monday afternoon. A week earlier, Biden had a lead of 4.8 percentage points.Both candidates traveled to Pennsylvania to make one last push on the final day before the election. Biden, who has roots in the Keystone State, has made more trips there than to any other state since securing the Democratic nomination.”I think we’re going to have a tremendous day tomorrow,” Trump said at a rally in Pennsylvania, the second of five on his schedule Monday as part of his sweep of crucial swing states. “I think you’re going to see a great red wave tomorrow.”The 2020 race has already set turnout records: Early voting and mail-in voting totals already comprise roughly two-thirds of all votes cast in 2016. In Texas — a traditionally Republican-leaning state that Democrats hope to blue in the current cycle — early voting has already surpassed the total number of ballots counted in 2016.But that phenomenon has raised concerns about how quickly the flood of mail-in votes will be processed and counted.More Democrats than Republicans have cast their votes by mail, according to data compiled by the U.S. Elections Project. But some states start counting those votes later than others, leading to fears that Election Night totals may present a misleading picture of who’s ahead before all the votes are tallied.Trump has recently claimed on Twitter that the U.S. “must have [its] final total on November 3rd,” even though numerous states have previously established systems that allow them to add votes after Election Day if they are not finished counting by that point.Meanwhile, analysts’ forecasts continue to show that not only is Biden favored to win the Electoral College, but also that Democrats could significantly expand their majority in the House, and possibly even win control of the GOP-led Senate.