WASHINGTON -- President Donald Trump ended his weekend stay at his Bedminster golf course Sunday afternoon, departing Morristown Airport with a one-time rival aboard Air Force One.

U.S. Sen. Rand Paul, R-Ky., had made an unannounced trip to New Jersey during the weekend and was spotted boarding the plane by the reporters who travel with the president.

"The president played a quick round of golf with Senator Rand Paul who the president really likes and enjoys spending time with," the White House said in a statement. "He also spent the weekend working on economic growth and making calls on the economy and national security."

Trump arrived at the airport from his Bedminster golf club at around 4:06 p.m., accompanied by first lady Melania Trump and their son, Barron.

The president has been a frequent guest all summer in New Jersey, including a 12-day stay earlier this month while renovations were underway at the White House.

Paul was one of the Republicans that Trump vanquished en route to the 2016 Republican presidential nomination, and he did not speak well of the senator during the campaign.

Truly weird Senator Rand Paul of Kentucky reminds me of a spoiled brat without a properly functioning brain. He was terrible at DEBATE! — Donald J. Trump (@realDonaldTrump) August 11, 2015

The president on Sunday also continued to rail against the investigation into whether his campaign colluded with Russia.

Study the late Joseph McCarthy, because we are now in period with Mueller and his gang that make Joseph McCarthy look like a baby! Rigged Witch Hunt! — Donald J. Trump (@realDonaldTrump) August 19, 2018

Special counsel Robert Mueller already has secured indictments or guilty pleas from 32 people, including four former Trump advisers, and three companies, according to Vox.

Earlier Sunday, the president's lawyer, former New York City Mayor Rudy Giuliani, went on NBC's "Meet the Press" and proclaimed, "Truth isn't truth."

It was reminiscent of Trump counselor Kellyanne Conway going on the same program after the January 2017 presidential inauguration and explaining that White House press secretary Sean Spicer was delivering "alternative facts" when he falsely said that Trump drew a bigger crowd than President Barack Obama did eight year earlier.

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant or on Facebook. Find NJ.com Politics on Facebook.