The U.S. Senate on Wednesday advanced a Coast Guard authorization bill that would allow federal money to be used to pay for design and engineering of the National Coast Guard Museum planned for downtown New London.

The bill, which authorizes $20.7 billion in funding for the Coast Guard over two years, initially passed the House in May but got tied up in the Senate due to a fight over discharge regulations for ships in the Great Lakes. With the Senate's approval, it will now go back to the House for a final vote, then to the president, if approved by the House as expected.

It opens the door for the Coast Guard to pay for design and engineering work to ready the museum for construction, but still prohibits the service from spending money on the actual construction.

"It's another congressional endorsement of the project, which I think has a powerful ripple effect as far as potential donors around the country who may have questions about whether this is a project that has the support of Congress," said U.S. Rep. Joe Courtney, D-2nd District.

Courtney and U.S. Sens. Richard Blumenthal and Chris Murphy, both D-Conn., successfully advocated several years ago to change a law to allow the Coast Guard to help pay for interior aspects of the museum, such as displays and exhibits.

The bill approved Wednesday would expand even further the scope of what the Coast Guard can pay for, Courtney said.

Blumenthal tried unsuccessfully to get rid of all limitations on Coast Guard funding for the museum. Congress giving the Coast Guard the green light to spend money on design and engineering would be a "major breakthrough," he said.

He said a priority next year will be securing another round of federal funding for the museum. He did not specify an amount, but said at least $5 million, likely more.

Asked whether his colleagues are satisfied with the pace of private donations, Blumenthal said "private money will be much easier to raise when the federal commitment is unequivocal and clear."

Murphy said in a statement that he'll continue to use his seat on the Senate Appropriations Committee to "secure funding for the museum."

To date, the National Coast Guard Museum Association, the fundraising arm for the museum, has raised $38 million for the estimated $100 million project. Of that, $5 million was from the federal government, $20 million from the state and $13 million from private donations.

Wes Pulver, a retired Coast Guard captain who is executive director of the museum association, said the hope is to get $30 million in total from the federal government.

The Coast Guard ultimately has the say in how it wants to devote its resources, and could decide not to spend money on design and engineering of the museum, even if given approval. Top brass in the Coast Guard repeatedly have talked about being strapped for resources and the need to modernize the service's fleet.

This year's authorization bill includes a 13.7 percent increase in funding from the last two-year authorization bill, according to Blumenthal's office.

The Coast Guard is reviewing an environmental assessment of the museum site on the downtown New London waterfront in a 100-year flood zone to determine the environmental impacts of the project. If the Coast Guard determines there's no significant impact, the project can proceed. Otherwise, it will direct museum organizers to work out any issues.

Environmental assessments were performed in 2002, 2008 and 2014, which concluded in a finding of no significant impact.

Preconstruction work, including site testing, started over the summer. Construction tentatively is scheduled to begin in 2021.