The news that Republicans had lost a Senate race in deep-red Alabama had barely hit before the recriminations started, and former Trump adviser Steve Bannon quickly emerged as a target.

Staunch conservative Roy Moore lost to Democrat Doug Jones, conceding a seat in a state where Democrats face nearly insurmountable odds.

Part of Mr Moore’s loss could likely be attributed to swirling allegations of sexual misconduct with teenagers (Mr Moore rejected those claims as false, saying “I have never engaged in sexual misconduct”).

But Republicans aligned with the Senate Majority Leader Mitch McConnell and the party establishment quickly turned their ire on Mr Bannon, a nationalist who broke with much of the party — and Mr Trump — by backing Mr Moore in the Republican primary in lieu of the more moderate Republican, Luther Strange. Taking aim at Republicans who had repudiated Mr Moore, Mr Bannon said on the eve of the election that there was a “special place in hell” for Republicans opposed to his candidacy.

“Not only did Steve Bannon cost us a critical Senate seat in one of the most Republican states in the country, but he also dragged the President of the United States into his fiasco,” Senate Leadership Fund CEO Steven Law — whose organisation is aligned with Mr McConnell and is dedicated to electing Republicans — said in a statement.

A former aide to Mr McConnell, Josh Holmes, also blasted Mr Bannon.

Alabama Senate race: Roy Moore vs Doug Jones Show all 12 1 /12 Alabama Senate race: Roy Moore vs Doug Jones Alabama Senate race: Roy Moore vs Doug Jones Democratic senatorial candidate Doug Jones speaks to reporters after voting Getty Images Alabama Senate race: Roy Moore vs Doug Jones Republican Senatorial candidate Roy Moore (L) and his wife Kayla ride their horses to the polling station to vote AFP/Getty Images Alabama Senate race: Roy Moore vs Doug Jones David Watson waves in a Santa suit as he holds a Doug Jones sign AP Alabama Senate race: Roy Moore vs Doug Jones Republican Senatorial candidate Roy Moore speaks to the media as his wife Kayla (R) looks on AFP/Getty Images Alabama Senate race: Roy Moore vs Doug Jones Democratic Alabama Senate candidate Doug Jones casts his vote at Brookwood Baptist Church REUTERS Alabama Senate race: Roy Moore vs Doug Jones Roy Moore speaks to the media after he rode in on a horse to vote AP Alabama Senate race: Roy Moore vs Doug Jones Democratic candidate Doug Jones greets supporters after casting his ballot AP Alabama Senate race: Roy Moore vs Doug Jones Republican Senate candidate Roy Moore departs on horseback after he cast his ballot in Gallant REUTERS Alabama Senate race: Roy Moore vs Doug Jones Voters wait in line to cast their ballot at a polling station setup in the St Thomas Episcopal Church Getty Images Alabama Senate race: Roy Moore vs Doug Jones Democratic Senatorial candidate Doug Jones (L) greets voters outside of a polling station at the Bessemer Civic Center Getty Images Alabama Senate race: Roy Moore vs Doug Jones Voters exit after casting their ballots at a polling station setup in the Fire Department Getty Images Alabama Senate race: Roy Moore vs Doug Jones Democratic Alabama U.S. Senate candidate Doug Jones speaks with the media after casting his vote at Brookwood Baptist Church Reuters

“I'd just like to thank Steve Bannon for showing us how to lose the reddest state in the union,” Mr Holmes said on Twitter.

Some Republicans reacted to Mr Moore's loss not with anger but with relief — among them Jeff Flake, an Arizona Republican who publicly announced he was donating money to Mr Jones and said, simply, “decency wins”.

Even before sexual misconduct allegations against Mr Moore emerged, he was a controversial figure. He was twice removed from the Alabama Supreme Court for defying the law, once for refusing to take down a monument to the Ten Commandments and once for ordering state judges to enforce Alabama’s ban on same-sex marriage despite the United States Supreme Court overruling state law in declaring same-sex marriage legal.

He has also argued a Muslim elected official should not be allowed serve in Congress, embraced a discredited conspiracy theory by questioning whether Barack Obama was born in the United States and called homosexual conduct “abhorrent” and “a crime against nature” that should be illegal.

After helping to mastermind Mr Trump’s presidential campaign and serving as a senior White House adviser, Mr Bannon exited the administration and returned to a leadership role at the far-right website Breitbart. He has described his role as ensuring Mr Trump stays faithful to the populist promises that helped him win the presidency.