PEMBROKE PINES, Fla. — With Election Day just three weeks away, President Trump and Democratic challenger Joe Biden concentrated Tuesday on battleground states both see as critical to clinching an Electoral College victory, tailoring their travel to best motivate voters who could cast potentially decisive ballots.

Biden was in Florida courting seniors, betting that a voting bloc that buoyed Trump four years ago has become disenchanted with the White House’s handling of the coronavrius pandemic. It was Biden’s third visit to the state in a month, after making targeted appeals to veterans and the Latino and Haitian communities.

Monday was the first day for advance voting in Georgia. President Trump and his Democratic challenger, former Vice President Joe Biden, concentrated Tuesday on battleground states both see as critical to clinching an Electoral College victory. Michael Holahan/The Augusta Chronicle via Associated Press

Trump was holding a rally later in Pennsylvania, Biden’s native state and one where the former vice president has spent far more time than in any other in recent months. Trump wants to hammer home the claim that a Democratic administration could limit hydraulic fracking in areas where the economy is heavily dependent on energy. It’s an effort to fire up a conservative base that Trump will have to turn out in droves to secure the 270 electoral votes needed to retain the White House.

The president also campaigned in Sanford, Florida, on Monday and will head back to the state on Friday.

The dueling trips come against the backdrop of a second day of hearings in the Senate to confirm Amy Coney Barrett to the Supreme Court. Trump and top Republicans see a swift confirmation just weeks after the death of Justice Ruth Bader Ginsburg as a chance to energize conservatives.

Biden’s campaign believes it can win the presidency without Florida’s 29 electoral votes, but it wants to lock up the state to pad a margin of victory over Trump, who has for months questioned the legitimacy of an election where many people will cast mail-in ballots during the pandemic. Biden has vowed to win Pennsylvania, but if he falls short, his path to victory narrows substantially.

Pennsylvania is the nation’s second-largest natural gas producer after Texas, and more natural gas was fracked from the state’s wells last year than in any previous year. Trump has repeatedly stated, falsely, that Biden will outlaw fracking. Biden has proposed only barring new leases on federal land, a fraction of U.S. fracking operations.

Democratic presidential candidate former Vice President Joe Biden speaks to members of the media before boarding his campaign plane at New Castle Airport, in New Castle, Del., on Tuesday, en route to Florida. Carolyn Kaster/Associated Press

In a Democratic primary debate in March, Biden misstated his fracking policy and his campaign quickly corrected that. Biden has otherwise been consistent, going so far as to tell an anti-fracking activist that he “ought to vote for somebody else” if he wanted an immediate fracking ban.

Trump also claims that Biden’s plan to lead the U.S. to net-zero emission of carbon pollution by 2050 would devastate the oil and gas industry in Pennsylvania, telling Pittsburgh voters recently: “I’ll keep your jobs in Pennsylvania where they belong and you’re going to be fracking for a long time.”

Trump narrowly flipped three Great Lakes states — Michigan, Pennsylvania and Wisconsin — in 2016, and he has virtually no path to reelection without holding at least one of them. Aides have concluded Michigan is likely out of reach. They have long viewed Wisconsin as his best option.

But his deficit in Wisconsin remains stubborn. And campaign aides acknowledge that even winning that battleground will not provide the needed votes if Biden claims Florida or the traditionally red state of Arizona.

The president’s travel this week reflects that bind. He’s visiting the three battleground states he likely can’t win without — Florida, Pennsylvania and North Carolina — as well as states he once thought were in his grasp — Iowa and Georgia — but where he now needs to play defense in light of recent polling showing Biden improving.

Trump traveled to Pennsylvania twice in the week before he tested positive for the coronavirus. With 20 electoral votes, the state is anchored by large cities — Philadelphia to the east, Pittsburgh to the west. But the rest of Pennsylvania is largely rural, comprised of small cities and towns where Trump ran up the score four years ago. He will need to again, in even greater numbers, as his prospects have slipped since 2016 in vote-rich suburban Philadelphia, where he underperformed by past Republican measures.

President Trump speaks during a campaign rally at Orlando Sanford International Airport on Monday in Sanford, Fla. Evan Vucci/Associated Press

That helps explain why Trump is holding a rally Tuesday at the airport in Johnstown in Cambria County, a historically coal and steel area that narrowly backed Barack Obama in 2008. But it has trended Republican for the past three decades and, in the 2016 election, Trump scored a 37 percentage-point victory. It is substantially whiter and has lower median incomes and lower rates of college-degree attainment than the rest of Pennsylvania.

Biden has also visited Johnstown, staging a drive-in rally at the train station while touring parts of Ohio and Pennsylvania by rail late last month. The former vice president has tried to cast himself as a champion of working-class voters while he accuses Trump of focusing on stock market returns and Park Avenue values. Biden says he would like to cut into Republican advantages in conservative areas, even if he cannot win them outright, saying that he’d like to make up for Democrats long ignoring white, working-class voters.

Despite the pandemic, Trump’s campaign has prioritized in-person events and aggressive door-knocking as it tries to turn out new and low propensity voters, including more members of the white working class who may have backed Democrats in the past but now favor the president.

Republicans point to an aging population and a shrinking voter-registration edge for Democrats, down 20% from 2016’s election to 717,000, according to the latest Pennsylvania data. The numbers also show that many more non-voting Democrats than Republicans fell off voter rolls in the last four years.

Associated Press writer Kevin Freking in Washington and Marc Levy in Harrisburg, Pennsylvania, contributed to this report.