WEST PALM BEACH, Fla. (AP) — President Donald Trump is cutting short his Florida vacation and returning to Washington on Thursday, one day earlier than expected for reasons the White House didn't explain.

The White House announced the abrupt change in the president's schedule late Wednesday, hours after Sen. Josh Hawley, R-Mo., said he will raise objections when Congress meets on Jan. 6 to affirm President-elect Joe Biden's victory in the November election.

The Republican challenge is a futile attempt intended to keep Trump in power, and a path the president has pursued after his campaign lost scores of legal challenges to the election outcome, including at the Supreme Court, and the Electoral College certified Biden's 306-232 win.

Trump's early return comes as tensions escalate between the United States and Iran in the final weeks of his administration. There is concern in Washington that Iran could order further military retaliation for the U.S. killing last Jan. 3 of top Iranian military commander Gen. Qassem Soleimani. Iran’s initial response, five days after that deadly U.S. drone strike, was a ballistic missile attack on a military base in Iraq that caused brain concussion injuries to about 100 U.S. troops.

Iranian-supported Shiite militia groups launched a rocket attack on the U.S. Embassy compound in Baghdad on Dec. 20. No one was killed, but Trump said days later that Iran was on notice.

“Some friendly health advice to Iran: If one American is killed, I will hold Iran responsible. Think it over,” Trump tweeted on Dec. 23. He added, ”We hear chatter of additional attacks against Americans in Iraq.”

His stand won the support of a key ally in Congress, Sen. Lindsey Graham, R-S.C.

``To the Iranians, if you’re going to try to do something on President Trump’s watch, you better be ready for a big pushback, so be careful what you do with Trump,’’ Graham told “Fox & Friends” on Thursday.

Trump, accompanied by his wife, Melania, arrived at his Mar-a-Lago home in Florida after dark on Dec. 23 and spent practically the entire vacation focused on trying to subvert the voters' will from last month's election.

Iran was an exception as he stayed mum on many other major developments during the holiday break, including a Christmas Day bombing in Nashville, Tennessee, the discovery in California and Colorado of a new and apparently more contagious variant of the coronavirus, and the death Tuesday of Rep.-elect Luke Letlow, R-La., from COVID-19 complications.

Trump's schedule change means he will miss the glitzy New Year's Eve party held annually at Mar-a-Lago.

Neither Trump nor the White House explained why he decided to shorten a vacation that had been expected to end on Friday.

Despite the plan by Hawley and group of Republicans in the Democratic-controlled House to object on Trump’s behalf during the counting of electoral votes, the challenge will not prevent Biden from being sworn in as president, and Sen. Kamala Harris, D-Calif., a Black woman of South Asian descent, from becoming vice president.

During his vacation, Trump also took near daily swipes on Twitter at Georgia Republican Gov. Brian Kemp and other state elections officials over his loss to Biden in that state.

Since losing the election and beginning a campaign to overturn the outcome, the usually chatty Trump has avoided engaging with reporters, even those who accompanied him to Florida. He went as far as barring them from his Christmas Day remarks to U.S. troops, which is the type of event the White House typically opens for news coverage.

Before he left Washington, Trump stunned Capitol Hill by objecting to spending — much of it sought by his own administration — in a government funding bill that had been paired up with a fresh round of needed coronavirus relief that included $600 payments to most individuals.

Trump jeopardized the financial aid and flirted with a government shutdown slated for last Tuesday by implying that he wouldn't sign the legislation unless lawmakers increased the payments to $2,000, a sum sought by most Democrats and some Republicans.

Trump eventually signed the bill Sunday night after several days of uncertainty in exchange for congressional votes on his aid demands. He also wants Congress to lift certain protections for social media companies and investigate his unfounded claims of fraud in the election.

Former Attorney General William Barr and other administration officials have said they saw no evidence of fraud on a scale massive enough to have changed the outcome of the election.

The House voted this week in favor of increasing the payments, but Senate Majority Leader Mitch McConnell, R-Ky., all but shut the door Wednesday when he declared that Congress had provided enough pandemic aid. McConnell blocked attempts by Democrats to force a vote in that chamber on the higher payments sought by Trump.