By David Morgan and Susan Cornwell

WASHINGTON (Reuters) -A bipartisan group of 10 senators is trying to build support for a new infrastructure plan to revitalize U.S. roads and bridges without raising taxes, three lawmakers said on Wednesday, a day after President Joe Biden rejected a separate Republican proposal.

Revamping America’s infrastructure is a high priority for Biden, but his proposal has run into trouble in a Congress only narrowly controlled by his fellow Democrats, making Republican support pivotal.

Republican Senator Mitt Romney told reporters that members of the group have reached “tentative conclusions” on their plan. It is expected to total nearly $900 billion. Biden had been pushing for a much higher figure, initially $2.3 trillion, but later lowered to $1.7 trillion.

“We’re not raising taxes,” Romney told reporters. “We’re going to be talking to other members to see if this can get enough support for this to have the necessary votes to be successful.”

The group includes Republicans Romney, Rob Portman, Bill Cassidy, Susan Collins and Lisa Murkowski and Democrats Kyrsten Sinema, Jon Tester, Joe Manchin, Mark Warner and Jeanne Shaheen.

“Taxes would be a huge mistake and I think the Biden administration understands that,” Portman said.

Biden has proposed raising taxes on U.S. corporations to help fund a sweeping package that would address traditional infrastructure projects as well as climate change and social programs. Republicans have shown no appetite for tax increases, having strongly backed a 2017 tax cut law signed by former President Donald Trump.

Tester said he would be willing to look at funding an infrastructure plan without raising taxes.

“I would consider it, sure,” Tester said. “I think there’s plenty of pots of money out there – hopefully they’re not all smoke and mirrors.”

Romney and Portman said members of the group have not settled on a total amount of infrastructure spending and declined to discuss specific provisions they would pursue.

“If we get good support, when we get that support, is when we’d talk about it, bring it out. If we don’t get the support, why, it’ll be closed down,” Romney said.

Portman said the group is looking at funding mechanisms for their proposal that could face Democratic resistance including unspecified user fees and tapping into funds for COVID-19 pandemic-related unemployment payments to individuals that some states have returned to the U.S. Treasury.

“I think the White House is interested in talking with us about appropriate ways to look at some COVID funding that’s being sent back,” Portman said.

Cassidy said he spoke to Biden by telephone on Tuesday to discuss infrastructure.

Most legislation requires 60 votes in the 100-seat Senate to move forward. The Senate is divided 50-50, with Democrats in control because Vice President Kamala Harris can cast a tie-breaking vote.

Biden broke off talks on Tuesday with Republican Senator Shelley Moore Capito, who had headed a six-member Republican team including party leaders and top members of relevant Senate committees.

Capito had offered Biden $330 billion in new infrastructure spending, far short of what he has sought.

The 10 senators now working on a new plan are part of a larger 20-member bipartisan group, known as the G-20, that includes Capito. Portman said he would continue to work closely with Capito and her team.

(Reporting by David Morgan; additional reporting by Susan Cornwell; Editing by Scott Malone and Chizu Nomiyama)