Transportation Secretary Pete Buttigieg sought to underscore the urgency of taking action to overhaul the nation’s infrastructure Thursday as he appeared before a key congressional committee, telling lawmakers they have “the best chance in any of our lifetimes to make a generational investment.”

The House Transportation Committee hearing was Buttigieg’s first appearance on Capitol Hill since his Feb. 2 confirmation. It comes as the administration is preparing a $3 trillion infrastructure and jobs package that is expected to call for a significant boost to transportation spending.

Buttigieg didn’t spell out new details of what the package might contain, but sketched out the administration’s broad goals.

“Wise transportation investments are key to making the American Dream accessible for all, leading our global competitors in innovation, getting people and goods where they need to be, creating good jobs — jobs that are union or pay prevailing wages — and tackling our climate crisis,” Buttigieg said.

He emphasized a desire to fix aging roads and bridges, encourage the adoption of electric vehicles, improve transportation options for people on foot and aboard buses, and to bring passenger trains up to par with those in other nations.

In pursuing those goals, the Biden administration also is aiming to battle climate change and foster racial equity. The infrastructure proposal could include some $400 billion to combat climate change.

President Biden is planning to travel to Pittsburgh on Wednesday to outline more details of the plan. At his first formal news conference Thursday at the White House, Biden said the future of the nation’s economic competitiveness relies on having a well-functioning transportation system.

“It’s the place where we will be able to significantly increase American productivity, at the same time providing really good jobs to people,” he said. “But we can’t build back to what they used to be. Global warming has already done significant damage.”

The administration is considering tax increases to fund the program. Buttigieg didn’t endorse any single approach but said lawmakers had the option to rely on fees on drivers, such as the gas tax, other general tax revenue or borrowing.

“I’ve heard loud and clear from members of Congress, Republican and Democratic, that an infrastructure proposal needs to have at least a partial funding source and I know that’s a challenging conversation,” he said.

Buttigieg has appeared regularly on television and at conferences to lay the groundwork for the administration’s infrastructure agenda and help promote the American Rescue Plan, the administratration’s $1.9 trillion stimulus package.

The next phase began Thursday as he appeared virtually to take questions from dozens of lawmakers, including Republicans skeptical of the administration’s focus on the environment and proposals that would raise taxes. In announcing the hearing, committee chairman Rep. Peter A. DeFazio (D-Ore.) had advised Buttigieg to “eat his Wheaties.”

Buttigieg took little direct criticism during the hours-long hearing, with many lawmakers using their time to delve into issues affecting their districts or niche policy areas.

The transportation secretary’s powers to enact an infrastructure agenda are sharply limited. The kinds of sweeping change the administration envisions would need the support of Congress. Biden has hosted two bipartisan groups of lawmakers at the White House to encourage them to work on infrastructure funding.

Buttigieg emphasized the support that transportation spending traditionally has enjoyed from both parties.

“Every citizen, regardless of political affiliation, shares the need for reliable roads, railways and air transportation,” he said.

Rep. Sam Graves (Mo.), the committee’s top Republican, said he was ready to collaborate but there were limits on what members of his party were willing to support.

“A transportation bill needs to be a transportation bill, not a Green New Deal,” he said. “It needs to be about roads and bridges.”

Lawmakers already have taken the first steps toward assembling a long-term road and transit funding package. DeFazio is seeking to use that package to achieve investment and environmental goals that are broadly similar to those Buttigieg has endorsed.

Opening the hearing, DeFazio linked his goals to those of the administration.

“I know you share my commitment to this vision,” he said. “Many of these principles overlap with the administration’s Build Back Better plan.”

The previous funding law was set to expire last year, when Democrats controlled the House and Republicans led the Senate, but was extended until the end of September. Despite rhetoric that infrastructure spending is bipartisan, in many cases, Democrats and Republicans disagree on how money should be used.

Rep. Hank Johnson (D-Ga.) asked Buttigieg about a long-standing policy of directing 2o percent of highway funds to transit projects. Some Democrats and urban transportation leaders want transit to have a greater share.

“Can we meet our transportation needs and respond to the climate crisis and connect all Americans to jobs and services by continuing the way we currently distribute federal funding for highways and transit?” Johnson asked.

Buttigieg has endorsed improving transit access but sidestepped the question.

“I believe by investing in transit, transit-oriented development, and for that matter rural main streets, in the right balance we can support people getting to where they need to be,” he said.

Rep. Brian Babin (R-Texas) asked whether the administration planned to set a date for phasing out sales of gasoline-powered cars, as California has done.

“I’ve not heard of anything to that effect at the national or federal level, although I would note that a lot of industry leaders, you know American auto companies, are moving in that direction already,” he said.

The path forward for infrastructure in Congress could be smoother with Democrats leading both chambers and holding the White House, but still, advancing a package through the Senate likely will require the support of several Republicans.

“I know that expectations have been raised before when it comes to major moves in American infrastructure,” Buttigieg said. “But now, in this season, we can turn aspirations into action.”