Christian Democrat (CDU) opposition leader Friedrich Merz dropped out as keynote speaker of a right-wing US-German political forum due to take place in Berlin at the end of August after receiving criticism for sharing space with far-right figures invited to the event.

The "Transatlantic Forum" was due to be hosted in Berlin by the representative office of the German state of Baden Wurttemberg.

However, the office said on Tuesday after further reviewing the guest list that it would not be hosting the event.

In a tweet, the office said some of the speakers showed a "close proximity" to the far-right Alternative für Deutschland (AfD) party.

"The event is therefore likely to damage the reputation of the state representation," the office said.

Merz's office did not give an explicit reason why the opposition leader pulled out, citing only a "change in the program."

It is unclear if the forum will go on after the keynote speaker and venue dropped out. 

Merz and Lindsey Graham were headliners

The event is being organized by German right-wing media organization The Republic and the US-based Tholos Foundation, which bills itself as an "advocate for free-market, low-tax and pro-competitive policies."

The keynote at the forum was to be a talk between the CDU's Merz and US Republican Senator Lindsey Graham on transatlantic relations.

After announcing his pullout, Merz's office said he still does intend to speak to Lindsay Graham in August, just not at the event.

Graham is known as a staunch supporter of former President Donald Trump, including after the 2020 election during which Trump refused to concede defeat.

The South Carolina senator is currently fighting a subpoena to testify in a grand jury investigation in the state of Georgia over his knowledge of "a multi-state, coordinated plan by the Trump Campaign to influence the results of the November 2020 election in Georgia and elsewhere."

Social Democrat (SPD) General Secretary Kevin Kühnert told Germany's t-online news website that it was striking for Merz to speak with Graham about "saving conservative values" given the "radicalization" of the Republican Party and Trump supporters who are "actively working to erode basic democratic rights."

Controversial right-wing guests

Another US conservative on the guest list is Grover Norquist, a longtime Republican political operative and gun lobbyist who sits on the board of the National Rifle Association (NRA) and is a vocal opponent of gun control in the US.

Norquist also rallies against any government spending and in 2015 said his goal is to "cut the government down to a size where we can drown it in a bathtub."

On the German side of the guest list, is Joachim Steinhöfel, a former attorney for the AfD, who represented the party's co-chief Alice Weidel in a 2018 defamation lawsuit against Facebook.

Also invited is polemicist and publicist Henryk Broder who, among other things, has argued Germany's Middle East policy appeases Islamists.

Green party deputy parliamentary group chairman Konstanin von Notz told the Redaktionsnetzwerk Deutschland (RND) group of newspapers that it was a politically untenable for a high-ranking politician like Merz to participate in such events. 

Von Notz added Merz needed to "recover his political compass." 

German journalist Miriam Lau reported that Merz had been unaware of the complete guest list, which ended up including included figures like Steinhöfel and Broder, when he first agreed to attend.