The Georgia US Senate candidate Herschel Walker has said he is “mad” at Donald Trump because the former president has claimed credit for asking the former NFL star to enter national politics.

Walker told the rapper and Revolt TV host Killer Mike: “President Trump never asked me … So, I’m mad at him.”

Trump championed a Walker run for the Republican nomination for US Senate before Walker announced it and then endorsed him. Walker went on to win in a round of primaries which saw other Trump-backed candidates struggle, including in Georgia where Brian Kemp dismissed a challenge from David Perdue for governor.

Walker, 60, was a running back who won the Heisman Trophy for best player in college football while at the University of Georgia, then played for the Trump-owned New Jersey Generals in the USFL before making his name in NFL with the Dallas Cowboys.

But his move into politics has stoked considerable controversy. Amid questions about his business record, his widely documented mental health struggles and his all-round suitability for a Senate seat, Walker skipped debates in the Georgia primary but won easily all the same.

In the aftermath of his win, CNN published a fact check of one of the many controversies surrounding the candidacy. Its headline: Herschel Walker falsely claims he never falsely claimed he graduated from University of Georgia.

Trump has helped steer a big football name into the US Senate before, championing the college coach Tommy Tuberville as he beat Doug Jones, a federal prosecutor and sitting senator, for a seat from Alabama in 2020. Tuberville then supported Trump’s attempt to overturn his defeat by Joe Biden.

Speaking to Killer Mike, Walker said: “One thing that people don’t know is President Trump never asked me. I need to tell him that he never asked. I heard it all on television that, ‘He’s going to ask Herschel,’ saying Herschel is going to run. President Trump never came out and said ‘Herschel, will you run for that Senate seat?’

“So, I’m mad at him, because he never asked, but he’s taking credit that he asked.”

Trump did not immediately respond. The question of to what extent the former president still controls the Republican party is a live one among observers and GOP power brokers, as Trump considers another run for the White House in 2024.

Walker continued: “Before all this coming about, my wife and I … we went into prayer and I prayed about it. And to be honest with you, I was praying to God to bring somebody else. ‘Oh my God, I am happy, my life is doing well …’ But I love the Lord Jesus.”

Walker’s opponent in the election in November will be Raphael Warnock, formerly a pastor at a church once home to the civil rights leader Dr Martin Luther King.

Warnock won the seat in a run-off in 2021, beating the Republican sports executive Kelly Loeffler to become the first Black Democratic senator from a southern state and the first Black senator of any party from Georgia.

Warnock’s win and that of Jon Ossoff over Perdue were crucial to Democrats regaining control of the Senate. Control of the chamber, and with it the Biden administration’s chances of any further legislative success, is in play again in the November elections.