WASHINGTON - With days to go before the Nov. 3 election, Republican President Donald Trump and Democratic presidential nominee Joe Biden are campaigning intensely in the closely contested "battleground" or "swing" states.
These states are important in the U.S. presidential election, where the winner is not decided by the popular vote. Instead, each state has a set number of electoral votes, which are awarded to one candidate or the other depending on the popular vote outcome in that state. In all but Maine and Nebraska, the candidate who gets the most popular votes in a state wins all of that state's electoral votes.
This "winner takes all" electoral system drives candidates to campaign more heavily in competitive states where victory could mean a clearer mathematical path to the White House.
Closely contested states that could "swing" toward either party, such as Pennsylvania, receive more attention from candidates than other states, such as California, where one party is almost certain to receive a majority of votes.
2020 Swing States
About a dozen states are considered "perennial" swing states because they have repeatedly had close contests in recent presidential elections. Six of those are seen as top prizes in 2020 because their large populations give them more electoral votes. They are Arizona, Florida, Michigan, North Carolina, Pennsylvania and Wisconsin.
Trump won all six states in 2016 by razor-thin margins, some less than a percentage point, but polls currently indicate a small lead for Biden in all six.
Swing States closer than national polls
Trump's 2016 victory in those six states followed a similar pattern to that in the rest of the country - Democratic advantages in urban centers were offset by capturing Republican-friendly voters in rural counties and suburban areas, and among white non-college-educated voters.
Despite trends showing that Biden may be able to peel off some of those demographics in 2020, the Biden campaign has warned supporters not to be complacent.
"The reality is that this race is far closer than some of the punditry we're seeing on Twitter and on TV would suggest," Biden campaign manager Jen O'Malley Dillon wrote in a memo to supporters on Saturday. "In the key battleground states where this election will be decided, we remain neck and neck with Donald Trump."
Analysts say with Biden having enjoyed a stable lead in the polls for months, his campaign's main fear now is that he could win the popular vote but lose the electoral college vote -- as happened to Democratic candidate Hillary Clinton in 2016.
Here is what is happening in the states that both campaigns see as critical to winning the 2020 presidency.
Wisconsin, home to many rural and blue-collar white communities that make up the bulk of Trump supporters, was "the tipping point state" that mathematically put Trump over the top in 2016.
Wisconsin ranks among the worst-hit states by the pandemic. It also became a focus of a national debate on racial justice after the August police shooting of African American Jacob Blake in Kenosha, Wisconsin, which came amid months of national protests and unrest.
Both Trump and Biden visited Kenosha with different messages. Biden focused on combating systemic racism while the president doubled down on law and order.
Michigan, a manufacturing state, has been hard hit by the pandemic-induced recession with more jobs and businesses lost than in most parts of the country. The president has encouraged his supporters to blame the state's Democratic governor, Gretchen Whitmer, for its economic shutdown.
The Trump campaign is targeting Michiganders who view the Democratic environmental agenda as hurtful to workers who depend on a strong manufacturing base. Biden is pushing the message that Trump has "no plan to get the virus under control, no strategy for pulling our economy out of this recession." Biden has promised to invest in jobs and critical infrastructure in the state.
Born in Scranton, Pennsylvania, Biden has emphasized his working-class family roots to win back non college-educated white voters lost to Trump in 2016, the first time a Republican candidate had won the state since 1988.
Pennsylvania in 2020 is seen as more crucial for Trump. It could be the state to give Joe Biden his 270th electoral vote, said Robert Griffin, research director for the Democracy Fund Voter Study Group. "But it might not be that consequential if Pennsylvania were to go a different direction, given that Joe Biden also appears to be ahead in places like Florida and Arizona," he said.
Biden currently has a slight edge in Florida - home to one of the country's largest elderly populations - with a message that the administration's coronavirus mismanagement has taken the lives of too many seniors, a group more vulnerable to the pandemic.
Trump has emphasized Florida throughout his campaign, visiting his Mar-a-Lago resort often and boosting new voter registration in the state as part of a campaign strategy to turn out working-class white Americans who did not previously vote.
"If Joe Biden wins Florida, it's going to be very difficult for Donald Trump to put together the 270 electoral college votes necessary to win," said Republican pollster Whit Ayres of North Star Opinion Research. If Trump wins Florida, Ayres said, Biden still has other routes, albeit narrower ones, to winning 270 electoral votes.
With the exception of Barack Obama's victory in 2008, Republican candidates have won nine out of the last 10 presidential elections in North Carolina. Analysts see this as a sign of a broader shift in demographics in the southern part of the country, where an increasingly diverse population could benefit Democrats.
"It's difficult to imagine a path to the White House for Donald Trump in particular, that does not go through to North Carolina," said Chris Cooper, a professor of political science from Western Carolina University.
The South has been a stronghold for the Republican Party for well over a decade and, if Trump somehow loses North Carolina, the odds are greater that he would also lose Florida, Cooper added.
Arizona has voted Republican in every presidential election since 1952 with the exception of Bill Clinton's win in 1996.
The state is currently leaning toward Biden, a trend driven by growing Democratic strength among suburban voters and the state's increasingly diverse electorate, particularly the fast-rising number of Hispanic voters. Latinos accounted for roughly one in five Arizona voters in 2016, and Clinton won them handily in 2016.
Seniors will play a big role in deciding how the state will go in 2020. The state is home to many retirement communities, and its voters skew slightly older than the rest of the country.