During his own presidential campaign last year, Pete Buttigieg released a $1 trillion infrastructure plan that called for vast new investment in public transit to lift local communities.

Buttigieg didn’t reach the Oval Office, but on Friday, he stood before a deserted shopping mall in a swing state, extolling benefits of a $1 trillion infrastructure law signed at the White House and a light-rail extension on its way with federal assistance.

“That’s the basic role of government, to do the things that we can only do when we do them together,” said Buttigieg, standing amid palm trees and hulking remnants of Phoenix’s Metrocenter mall, which shuttered during the pandemic downturn. The rail project in the nation’s fifth-largest city will anchor the type of rebirth the transportation secretary hopes to make possible all around the country.

His presidential bid didn’t last until the Arizona primary. But his role overseeing hundreds of billions of dollars in infrastructure funds puts Buttigieg at the center of one of the chief accomplishments of the Biden administration with implications for his boss’s future and his own, as he was handed the resources to uncork ambitious projects, elevating local ideas and reshaping federal transportation priorities.

About $1 billion in grants the department awarded Friday offers a taste of the goals of the administration as it eyes far bigger spending through the infrastructure package. Buttigieg prioritized equity and environmental criteria in making the awards and shifted emphasis away from the road efforts which the Trump administration had favored.

But the new law also limits power in Washington to require sweeping changes. Implementing it will test the former mayor’s management and political skills in a divided country with its far-reaching transportation challenges and contrasting visions on how to solve them. The work will draw scrutiny and partisan broadsides, while offering an opportunity to leave a lasting mark and expand his national footprint.

Rep. Anthony G. Brown (D-Md.), a member of the House Transportation Committee, said Buttigieg’s experience as a mayor has prepared him for such an undertaking by government. In South Bend, Ind., Buttigieg made downtown streets more friendly to pedestrians and cyclists, a strategy he now has the power to support all across the country.

“His record has demonstrated his understanding and his commitment to these types of programs and initiatives,” said Brown, a national chair for Buttigieg’s presidential campaign. “It’s a much larger investment pool than he’s managed before, but quite frankly, that could be said for anyone and everybody who would serve as secretary of transportation.”

Buttigieg’s supporters say he is focused on implementing the infrastructure law but note that his success could lift future aspirations.

“Will it have incidental benefits to his professional career? Absolutely,” Brown said. “The same can be said of anyone who steps into a position where you have a meaningful impact.”

The infrastructure law guarantees the Transportation Department at least $567 billion over five years, a sum that far outpaces what other Cabinet agencies will receive, and gives Buttigieg a hand in projects in every state and territory. He will have to balance a hybrid role, at times greenlighting projects, at others serving as conductor.

There is a sharp increase in money available for competitive grant funds that Buttigieg and his team can choose how to send to cities and states, providing some of their best opportunities to determine what gets built locally. The infrastructure bill calls for $210 billion for competitive or discretionary grants, according to senior officials. While much of the funding is guaranteed, officials also noted that $93 billion is subject to future votes on Capitol Hill. Despite bipartisan support for those extra funds, political changes in Congress could shift priorities.

Reflecting the complexity of rules governing federal transportation dollars, the Infrastructure Investment and Jobs Act includes an even bigger pot of money that Buttigieg’s department is required to distribute to states based largely on existing mandated funding formulas. That leaves many critical spending decisions in the hands of states. It also sets up the potential for different states and levels of government to pull in different directions on some of the Biden administration’s top specific transportation priorities, such as addressing climate change as well as equity issues.

Delivering on that second prong could be especially helpful politically to Buttigieg, who struggled among Black voters who form a vital Democratic Party constituency. The new infrastructure law puts him in a position to address the kind of racist 20th century highway projects he has regularly mentioned since taking office as transportation secretary.

Some grants the department announced Friday would start that process. Atlanta will get $900,000 to study a project to help residents who live by interstates 75 and 85, which has severed historically Black communities, including the one where Martin Luther King Jr. was born, from downtown. The project would build a platform over the two highways to create a park and ways for people on foot and bikes to get across.

In New Rochelle, N.Y., officials secured $12 million from the department to turn much of an old, disjointed highway into a park. “Memorial Highway, the road in question, is a classic 1950s-era planning disaster,” said Noam Bramson (D), the city’s mayor. “In keeping with a theme we see all around the country, it bulldozed primarily a Black and Brown neighborhood and what was left was severed from our downtown core.”

New Rochelle had applied for the grant twice before. Bramson said that he thinks the new administration’s focus on equity got the project over the line this time. “I think it will be among the most significant and transformative projects in the city’s history,” the mayor said, and is something which he hopes could be replicated for other communities.

The approach favored by the Transportation Department has its detractors. Rep. Garret Graves (R-La.), a member of the Transportation Committee, blasted the grant selections this week. He criticized the choice of projects that would fund parks or tackle health inequity, and said the department favored projects in districts represented by Democrats, which officials said wasn’t intentional. “This is supposed to be a transportation program,” Graves said in a statement. “We sit in traffic and they get green space.”

As focus shifts to the much bigger dollar amounts in the infrastructure law, partisan fights over transportation policy are likely to continue. Rep. Sam Graves (Mo.), the Republican leader on the Transportation Committee, said that he plans to closely track the expenditures and be ready to “act accordingly the instant we sense any potential waste, fraud, or abuse.”

“It’s difficult to see how they can issue funds quickly while still complying with all the new policy requirements and rolling back various regulatory reforms from the previous administration,” Graves said in a statement.

The last time the Transportation Department was handed such a large pot of new federal money was during passage of the American Recovery and Reinvestment Act early in the Obama administration. The goal then was to push money into the “shovel-ready” projects. Officials now say they are more interested in what is “shovel-worthy.”

Ray LaHood, the transportation secretary at the time, said he formed a group inside the department and worked with leaders in states and cities to ensure money was spent wisely. It was fewer federal dollars then, LaHood said, but the concept is the same. “Even though they have an enormous amount more money, it’s still going to roads and bridges and transit and ports and other infrastructure,” he added.

Buttigieg’s push for transportation changes in South Bend, population 103,000, initially met pushback, with some residents skeptical of a vision dubbed “complete streets.” Changes were meant to improve life downtown by making walking safer and more attractive, but some drivers worried it would gum up their attempts to get through.

As impassioned as critics were then, Buttigieg and the administration are facing new levels of partisan opposition in Washington. President Biden has argued the infrastructure law is proof that American democracy can work. But while more than a third of Senate Republicans voted for the bill, just 6 percent of House Republicans did, laying bare deep divisions in a realm with many shared interests.

Buttigieg argued that lessons in South Bend still hold sway. “One of the great things about good design and infrastructure is seeing is believing, and you see that progress from skeptics to converts,” he said. Back home in Indiana, that entailed a process where everyone, including himself, had to adapt, he said, using an approach that also applies to implementing the infrastructure law, since it falls to states and local governments to deliver projects with the federal dollars.

But Buttigieg has said he also sees a difference between now and his time as mayor. While it took work to move public opinion in South Bend, he said “public opinion was right there with the administration from day one” on infrastructure. Those on Capitol Hill who saw political risk in supporting the law “will come to see that the public really is excited for and impatient for all these improvements.”

Despite a key increase in money, intense competition for transportation funding is likely to continue, with demand for grants outpacing supply many times over. On Monday, Rep. Bobby L. Rush (D-Ill.) approached Buttigieg at the signing of the infrastructure law to personally give him a letter outlining the importance of a rail extension for Chicago.

He noted how the line’s terminus, dozens of blocks from the city border, creates obstacles for people trying to reach their destinations. An infusion of cash from Washington, he said, could increase access to good jobs for those residents “suffering second-class citizenship. I wanted to make sure that he walked away from there with my priorities in his pocket.”