Former New York Mayor Rudy Giuliani just made a major decision to switch law firms, but the one-time GOP presidential contender says he’s still weighing an even tougher choice: whom to back in the 2016 race.

“It is really very hard. I have four very good friends running for president,” Giuliani told CQ Roll Call on Wednesday. “Donald Trump has been my friend for 25 years; our families know each other.”

Giuliani said he’s also close with former Florida Gov. Jeb Bush, as the two have campaigned for each other over the years, and with Sen. Marco Rubio, a Florida Republican. He called New Jersey Gov. Chris Christie “like a brother.”

“I’m going to make an endorsement the morning I wake up and have come to a conclusion on who can beat Hillary Clinton,” Giuliani said.

Giuliani left Bracewell & Giuliani, now called simply Bracewell, for a New York-based perch at the international law and lobbying firm Greenberg Traurig. He is global chairman of Greenberg’s cybersecurity and crisis management practice and will house his own ventures — Giuliani Partners and Giuliani Safety & Security — in Greenberg’s offices.

The former mayor, whose work after the 9/11 terrorist attacks made him a national figure, was an early leader in public opinion polls for the 2008 GOP presidential nomination. But Giuliani never gained traction in the early contests, and dropped out after his friend and eventual nominee Sen. John McCain won the Florida primary. 

Giuliani said he will advise Greenberg’s clients on legal matters and will not lobby, but he admits he can’t steer clear of politics.

The rise of outsider candidates such as Trump and Sen. Ted Cruz, R-Texas, reveals Americans’ frustration with government that has been escalating for years, Giuliani said. He said the declining approval ratings of Congress should make it no surprise.

“I think they’ve actually come to the point where they blame it on both parties,” he said of American voters. “When a person like a Trump comes along or, to some extent Cruz, who has made himself sort of an outsider [candidate], I think it’s very appealing. That is a real sentiment that is very, very powerful, very strong.”

Though he has been an unapologetic critic of President Barack Obama, Giuliani said he believes the president has an “appreciation” of the dangers of cyberattacks. And he called the president “a good man, an honest man — I just think on policies he’s mostly wrong.”

The former mayor said he doesn’t wish to take back his much-criticized comment at a fundraising dinner last year that Obama doesn’t “love” America. Giuliani said Wednesday Obama looks at America in a more critical way than he does, but that the Republican believes Obama “loves his version of America.”

“I don’t regret it; I don’t take it back — this is why I’m such a good friend of Donald Trump,” Giuliani said, “because I don’t take anything back.”