“My takeaway is there is a genuine understanding that infrastructure is a major issue for the U.S.,” said Mitch Simpler, chairman of the American Council of Engineering Cos., one of the hosts. “The only difference between the candidates is what to do and when to do it.”

Four of the top contenders—former Vice President Joe Biden, Sen. Amy Klobuchar, former Mayor Pete Buttigieg, and businessman Tom Steyer—addressed the conference at the University of Nevada, Las Vegas.

All vowed to reach out to Republicans because, they said, both political parties know infrastructure is too important to be held hostage to partisanship.

“We have an opportunity to take infrastructure week from being a punchline and make it a template for the future,” Buttigieg said.

Buttigieg, former mayor of South Bend, Ind., says infrastructure “is a mayor’s native language” and that the federal government could learn from states and municipalities that regularly find room for compromise on road and water projects.

Biden challenged Republicans to come to the table, saying the GOP has previously supported infrastructure “from the Erie Canal going forward.”

He said he would like to raise the corporate income tax rate to 28% to fund his $1.3-trillion infrastructure plan, which includes building 500,000 electric-vehicle charging stations this decade.

Biden said he would look favorably at increasing the federal passenger facility charge on air travelers, which funds airport improvements, but opposes raising the federal gasoline tax, which funds highway projects.

“We’re not going to be able to raise the gas tax; we may be able to index it down the line,” he said.

Klobuchar, the Minnesota senator who scored a surprising third-place finish in the New Hampshire primary, said she has seen firsthand the life-and-death importance of reliable infrastructure.

“I actually live just eight blocks from where the I35-W bridge fell down” in 2007, killing 15 people, she said. “A bridge just doesn’t fall down in the middle of America.”

Klobuchar told the audience: “We had to fix it; we did,” and the bridge was rebuilt in just 13 months. She said her $1-trillion infrastructure plan will be her top legislative priority. Like the other candidates, Klobuchar’s proposal includes funding to build rural Internet broadband.

“Farming has become increasingly high-tech,” she said.

Steyer promised “the biggest building project in American history.” He pledges $450 billion for maintenance of existing infrastructure, along with $775 billion for clean-transportation infrastructure, including mass transit.

“We can’t go the rest of our lives depending on single-family cars,” he said.

President Donald Trump, the presumptive Republican nominee, and Democratic candidates Sens. Bernie Sanders and Elizabeth Warren declined invitations to appear at the Vegas event.

Event sponsors included the International Union of Operating Engineers; Transportation Trades Dept., AFL-CIO; North America’s Building Trades Unions; Transport Workers Union of America; American Society of Civil Engineers; American Public Transportation Association; American Council of Engineering Cos.; American Road and Transportation Builders Association; Value of Water Campaign; Association of Equipment Manufacturers; Airports Council International-North America; and Build Together.