California Gov. Jerry Brown (D) participates in a climate change workshop organized by the Vatican on Nov. 4, 2017. (Alessandra Tarantino/AP)

California Gov. Jerry Brown's recent trip to the capital of the European Union had all the trappings of a visit by a head of state — he even got an upgraded title.

"Mr. President, welcome in Brussels," Brown (D) was told this month as he exited his Mercedes van in front of the European Parliament in the spot usually reserved for national leaders. Then he was whisked off to a day of hearings, testimony and high-level meetings in the heart of European power.

Nearly a year into the Trump presidency, countries around the world are scrambling to adapt as the White House has struggled to fill key government positions, scaled back the State Department and upended old alliances. Now some nations are finding that even if they are frustrated by President Trump's Washington, they can still prosper from robust relations with the California Republic and a constellation of like-minded U.S. cities, some of which are bigger than European countries.

Brown's 10-day trip to Europe, which ended Tuesday, was just the latest in a growing transatlantic back-and-forth that bypasses the Trump-era White House. In July, New York Mayor Bill de Blasio headlined a protest in Hamburg against the Group of 20. Several European countries have stationed ambassadors in Silicon Valley to boost trade ties.

Meanwhile, state and municipal governments are expanding or building new offices to help them manage the increased interest in Europe and Asia. This year, Los Angeles Mayor Eric Garcetti (D) created the position of deputy mayor for international affairs to better manage relations with foreign governments.

Last week Garcetti huddled in Los Angeles with the Israeli president and Armenian defense minister. The latter stopped by on his way to a peacekeeping conference and briefly described his country's ongoing dispute with Azerbaijan over the breakaway Nagorno-Karabakh region.

The mayor's motives for taking the meeting were simple. "We have a big Armenian population in Los Angeles that cares about events in Armenia," said Nina Hachigian, who filled the international affairs position and previously served in the Obama administration as U.S. ambassador to the Association of Southeast Asian Nations in Jakarta, Indonesia.

Many world leaders say they have no illusions that they can avoid the White House on critical issues at the core of global stability, especially those related to security. But they have embraced efforts by Democratic governors and mayors to present a different face of U.S. power to the world, albeit at a lower level than the White House or State Department.

"There is an impression by politicians here that President Trump in person is no longer the voice of the free Western world," said Christian Ehler, a German lawmaker who heads the European Parliament's delegation for relations with the United States and helped broker Brown's visit to Brussels. "We are much more carefully looking now to the diversity of what is being discussed in the United States, and we see that California is one of the powerhouses of the world economically."

European leaders said they have been frustrated by the Trump administration's unprecedented slowness in filling senior political jobs at the State Department and Pentagon, which has given them few policy interlocutors in Washington.

Ambassadors complain that even when they can secure meetings with administration officials, the policy is often unclear.

"The problem is that people don't know anything," said one Eastern European ambassador in Washington who spoke on the condition of anonymity to share his frank opinion. "They are quite open about it. . . . It doesn't matter what level. It is all levels."

In meetings with Trump to present their credentials, European ambassadors said the president was laser focused on two subjects. He wanted to know how much their countries were spending on defense and the size of their trade deficit with the United States, two ambassadors said.

In Europe, leaders have been especially frustrated by Trump's June decision to pull out of the Paris climate agreement, viewing it as a gratuitous slap at them on one of their top priorities. So they welcomed Brown's climate-change-focused trip, which was built around global-warming talks taking place in Bonn.

Ehler said that although European countries always have had robust ties with U.S. cities and states for business reasons, the center of their conversations had shifted since Trump took office.

In the past, he said, the federal government was the focus on most big issues. Now when governors and mayors come to visit, "climate change or environmental issues, or regulatory issues, are the focus. Because these issues are dropping down from the capital level to the state or community level," Ehler said.

In the United States, local governments are still figuring out how best to influence policy debates and work with international partners.

"We don't have a separate foreign policy. We have initiatives and city-to-city cooperation," said Hachigian, who leads a seven-person foreign affairs team that includes former Pentagon and State Department officials. She said she has been flooded with applications from Foreign Service officers who over the first 11 months of the Trump administration have fled the State Department.

Garcetti's discussions with foreign leaders at home and overseas often focus on disaster response, trade, water conservation, homelessness and sustainability.

"We can create ties that could be useful and some consolation, given the difficulties that our foreign counterparts are having with Washington," she said.

In Brussels, Brown got the welcome of a global leader, delivering an address in the vast European Parliament hemicycle from the same rostrum as German Chancellor Angela Merkel when she is in town. Brown commanded applause at a Vatican environment conference; joined the Democratic governors of Washington, Oregon and Virginia at the Bonn climate gathering; and was feted by E.U. ministers for his efforts to combat rising greenhouse gases.

Brown said that he was happy to take on the role of a U.S. emissary even if he cannot negotiate treaties.

"I don't think we can confine our thinking just to federal employees," Brown told a small group of reporters.

"I have an opportunity to talk to a lot of national leaders, and so that's good," he said. Contact between U.S. states and other countries can be "helpful and important, because you have to keep talking. This business of yelling at each other across the ocean is not good."

The trip followed the California governor's June decision to sign a joint statement with the German government on climate cooperation, an unusual move by a U.S. state and an entire nation to work together to fight rising temperatures. Next September, Brown plans to host a global climate summit in San Francisco intended to support the same Paris climate agreement that Trump plans to exit.

Top officials who met with Brown said they were delighted to encounter a friendly American voice.

"The engagement against climate change must be global," said European Parliament President Antonio Tajani as he spoke at a news conference alongside Brown and senior European officials. "In the United States, there are several governors working in the right direction, even if the Trump government decided to change the line. What they are trying to do in the government of Mr. Brown is very interesting."