US President Joe Biden greets supporters and volunteers during a campaign stop at a Biden-Harris campaign office in Harrisburg, Pennsylvania, on July 7, 2024. Biden is back out on the campaign trail Sunday, desperate to salvage his re-election bid as senior Democrats meet to discuss growing calls that he quit the White House race. The 81-year-old Democrat kicks off a grueling week with two campaign rallies in the battleground state of Pennsylvania, before hosting the NATO leaders' summit in Washington. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)

US President Joe Biden greets supporters and volunteers during a campaign stop at a Biden-Harris campaign office in Harrisburg, Pennsylvania, on July 7, 2024. Biden is back out on the campaign trail Sunday, desperate to salvage his re-election bid as senior Democrats meet to discuss growing calls that he quit the White House race. The 81-year-old Democrat kicks off a grueling week with two campaign rallies in the battleground state of Pennsylvania, before hosting the NATO leaders' summit in Washington. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)

US President Joe Biden shakes hands with a supporter during a campaign stop at a Biden-Harris campaign office in Harrisburg, Pennsylvania, on July 7, 2024. Biden is back out on the campaign trail Sunday, desperate to salvage his re-election bid as senior Democrats meet to discuss growing calls that he quit the White House race. The 81-year-old Democrat kicks off a grueling week with two campaign rallies in the battleground state of Pennsylvania, before hosting the NATO leaders' summit in Washington. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)

US President Joe Biden greets supporters and volunteers during a campaign stop at a Biden-Harris campaign office in Harrisburg, Pennsylvania, on July 7, 2024. Biden is back out on the campaign trail Sunday, desperate to salvage his re-election bid as senior Democrats meet to discuss growing calls that he quit the White House race. The 81-year-old Democrat kicks off a grueling week with two campaign rallies in the battleground state of Pennsylvania, before hosting the NATO leaders' summit in Washington. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)

US President Joe Biden greets supporters and volunteers during a campaign stop at a Biden-Harris campaign office in Harrisburg, Pennsylvania, on July 7, 2024. Biden is back out on the campaign trail Sunday, desperate to salvage his re-election bid as senior Democrats meet to discuss growing calls that he quit the White House race. The 81-year-old Democrat kicks off a grueling week with two campaign rallies in the battleground state of Pennsylvania, before hosting the NATO leaders' summit in Washington. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)

US President Joe Biden reacts to children while greeting supporters and volunteers during a campaign stop at a Biden-Harris campaign office in Harrisburg, Pennsylvania, on July 7, 2024. Biden is back out on the campaign trail Sunday, desperate to salvage his re-election bid as senior Democrats meet to discuss growing calls that he quit the White House race. The 81-year-old Democrat kicks off a grueling week with two campaign rallies in the battleground state of Pennsylvania, before hosting the NATO leaders' summit in Washington. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)

US President Joe Biden greets supporters and volunteers during a campaign stop at a Biden-Harris campaign office in Harrisburg, Pennsylvania, on July 7, 2024. Biden is back out on the campaign trail Sunday, desperate to salvage his re-election bid as senior Democrats meet to discuss growing calls that he quit the White House race. The 81-year-old Democrat kicks off a grueling week with two campaign rallies in the battleground state of Pennsylvania, before hosting the NATO leaders' summit in Washington. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)

US President Joe Biden greets supporters and volunteers during a campaign stop at a Biden-Harris campaign office in Harrisburg, Pennsylvania, on July 7, 2024. Biden is back out on the campaign trail Sunday, desperate to salvage his re-election bid as senior Democrats meet to discuss growing calls that he quit the White House race. The 81-year-old Democrat kicks off a grueling week with two campaign rallies in the battleground state of Pennsylvania, before hosting the NATO leaders' summit in Washington. (Photo by SAUL LOEB / AFP) (Photo by SAUL LOEB/AFP via Getty Images)