BUENOS AIRES, Argentina — President Donald Trump landed here Thursday night with special counsel Robert Mueller looming over his shoulder back home and President Xi Jinping of China on his horizon.

The trick for him, as he celebrates the signing of a new trade agreement with Mexico and Canada Friday and negotiates over his trade war with China Saturday, is to prevent his domestic troubles from damaging American foreign policy interests as the G-20 meets here.

Rep. Gerry Connolly, D-Va., a member of the House Foreign Affairs Committee, said that the "dark cloud" of the Mueller probe could affect not only Trump's "state of mind" and ability to deal with foreign leaders but his counterparts' approach toward him.

"Certainly, they don't see in front of them a strong leader with a unified country at his back," Connolly said in a telephone interview with NBC News.

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Already, there are signs that it is proving difficult for Trump to separate domestic politics from his agenda at this conference.

Shortly after he found out Wednesday morning that former ally Michael Cohen had pleaded guilty to lying to Congress to obscure his efforts to build a Trump Tower in Moscow during the 2016 presidential campaign, Trump abruptly canceled a planned meeting here with Russian President Vladimir Putin.

Trump, who announced the decision while aboard Air Force One, attributed the decision to Russia's refusal to release captured Ukrainian sailors and ships. But Michael McFaul, the former U.S. ambassador to Russia under President Barack Obama, questioned the timing of the two events in an interview with MSNBC's Andrea Mitchell Thursday.

"He never criticized Vladimir Putin directly for attacking these Ukrainian sailors. Then the news about Michael Cohen drops and just a few minutes later, he decides to cancel the meeting," McFaul said. "It's very unusual that it would be canceled over Twitter, let alone unilaterally."

Russian Foreign Ministry spokeswoman Maria Zakharova said Friday that she doesn't believe Trump canceled because of concern over the conflict between her country and Ukraine.

"Was Ukraine’s provocation in the Kerch Strait the true reason for the cancellation? We have heard the official explanation and taken note of it," she said. "But is it true? I think the true reason is rooted in the domestic political situation in the United States, which is crucial for decision-making.”

The president’s reception in Buenos Aires seemed to hint at a diminished status. When Xi arrived earlier in the day, he was greeted with a red carpet and a military band. Saudi Crown Prince Mohammad bin Salman had been given the red carpet but no band. Yet, as Trump was met by a small delegation of dignitaries, for whatever reason, he was afforded neither honor.

On Friday, before an early-morning meeting with Argentinian President Mauricio Macri, Trump fired off a two-tweet thread about the Mueller investigation.

Oh, I get it! I am a very good developer, happily living my life, when I see our Country going in the wrong direction (to put it mildly). Against all odds, I decide to run for President & continue to run my business-very legal & very cool, talked about it on the campaign trail... — Donald J. Trump (@realDonaldTrump) November 30, 2018

....Lightly looked at doing a building somewhere in Russia. Put up zero money, zero guarantees and didn’t do the project. Witch Hunt! — Donald J. Trump (@realDonaldTrump) November 30, 2018

Matt Schlapp, chairman of the American Conservative Union and a close ally of Trump, said that the president won't be affected by the latest turn in Mueller's investigation of his ties to Russia.

"A long time ago, President Trump realized the awful truth of what he is facing with the Mueller probe, and he's able to deal with that and the other responsibilities of being president at the same time," Schlapp said.

Still, whatever the cause of his decision to scrap the long-discussed face-to-face with Putin, it's clear Trump is devoting more time to Mueller and less time to foreign leaders than originally planned. The White House announced Thursday that his scheduled meetings with Turkish leader Recep Tayyip Erdogan and South Korean leader Moon Jae-in would be reduced to informal pull-asides.

And after sending his Friday morning tweets, Trump was late for the 7:05 a.m. local time (5:05 a.m. ET) meeting with Macri.

Trump's schedule Friday currently calls for bilateral sessions with Macri, Japanese Prime Minister Shinzo Abe of Japan and German leader Angela Merkel, the USMCA trade pact signing and a meeting of the full set of G-20 countries.

Still, the big focus of the summit for Trump remains the same: His Saturday dinner date with Xi.

Laura Rosenberger, director of the Alliance for Securing Democracy and a former foreign policy adviser to 2016 Democratic presidential nominee Hillary Clinton, said Trump's emphasis on tariffs is "playing into Xi's hands" by "making the whole of the relationship" about that rather than China's broader economic practices and its promotion of technology across the globe.

"What I have not seen from the president or this administration is a real China strategy," Rosenberger said. "Because of that Xi and the Chinese government are running circles around us."

Connolly noted that Trump's past trips have often ended with allies rankled and adversaries emboldened. For example, Trump trashed a G-7 meeting, along with host Prime Minister Justin Trudeau of Canada, from Air Force One as he left, while he declared victory after summits with Putin and North Korean leader Kim Jong Un.

"The only summits he seems to have left feeling good about were with foes," Connolly said. With allies, "he's just left wreckage in his wake — if he can avoid that, I'll settle for that."

The fear among Trump's critics is that the latest developments in the Mueller probe — the focus of many of Trump's recent tweets — will interfere with his ability to stay focused.

"It would take an impressive dexterity to be able to separate the Mueller probe hanging over the president's head from the work that lies ahead domestically and across the globe," said Scott Mulhauser, a Democratic strategist and former chief of staff at the U.S. embassy in Beijing. "So the likelihood that fears, concerns and anger about Mueller bleed into his exchanges with 19 other world leaders is high — and potentially perilous."