Multiple sources close to Sen. Ted Cruz Rafael (Ted) Edward CruzThe Hill's Morning Report - Sponsored by Facebook - Washington on edge amid SCOTUS vacancy Murkowski: Supreme Court nominee should not be taken up before election Battle lines drawn on precedent in Supreme Court fight MORE (R-Texas) say he will finally endorse Donald Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE as soon as Friday, according to Politico.

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It is unclear whether Cruz plans on just pledging to vote for the GOP presidential nominee or offering more substantial backing.

Cruz has repeatedly refrained from backing Trump after their bitter clash in the Republican presidential primary.

The senator shocked listeners by refusing to endorse Trump during his speech at the Republican National Convention in July, where he was booed.

“To those listening, please, don’t stay home in November,” he said.

“Stand and speak and vote your conscience, vote for candidates up and down the ticket who you trust to defend our freedom and be faithful to the Constitution.”

Cruz mentioned Trump once during his remarks, congratulating him on winning the GOP nomination. Trump had previously vowed to back the eventual nominee.

The Texas lawmaker defended his decision the following morning before his state's delegation, citing Trump's personal attacks on his family.

“I am not in the habit of supporting people who attack my wife and attack my father,” Cruz told the Texas delegation at a convention breakfast on July 21.

“Neither he nor my campaign has taken back a word of what they said about my family."

Trump floated rumors alleging Cruz’s father was involved in the assassination of former President John F. Kennedy, and he angered Cruz when he tweeted an unflattering photo of his wife, Heidi.

Cruz, who may face a primary challenge in 2018, has faced mounting pressure to back Trump before Election Day.

Trump said in late July he would not accept Cruz’s nomination and said it would have boosted the senator’s stock for a 2020 presidential bid if given earlier.

Trump’s campaign on Wednesday, however, joined Cruz in rejecting a plan for the U.S. to cede control of functions critical to the Internet.

This story was updated at 2:40 p.m.