In this Dec. 28, 2011 photo, traffic moves across the Highway 520 floating bridge toward Seattle. (AP Photo/Elaine Thompson)

If the federal government could do just one thing for San Francisco and Seattle, it would be to help build out urban infrastructure, the cities’ mayors said.

In a wide-ranging interview ahead of a White House meeting on Friday, the mayors of both cities discussed the issues confronting their — and other — cities, such as homelessness, affordable housing, foreign trade, minimum wage increases, education and economic development. But infrastructure was the one issue both returned to most frequently.

“Post-World War II, with the suburbanization of America, the federal government stepped in big time and created an interstate system that supported the suburban lifestyle,” Seattle Mayor Ed Murray (D) said. “As we urbanize as a country, we need the federal government to step in big time with transit for our urbanization.”

Infrastructure support is a major theme of the annual winter meeting of the U.S. Conference of Mayors in Washington, D.C., this week. In his Tuesday night State of the Union address, President Obama called on Congress to pass a bipartisan infrastructure plan, while Vice President Biden echoed that call on Thursday in a speech to the group of mayors.

While Republicans typically oppose a big federal footprint, there is support for striking a deal on infrastructure. Environment and Public Works Committee Chairman Sen. Jim Inhofe (R-Okla.), a staunch conservative, has even suggested the door may still be open to an increase in the gas tax, describing it as a user fee instead of a tax. And the issue remains bipartisan among mayors, said San Francisco Mayor Ed Lee.

“We’re all focused on infrastructure,” he said. “We think that that’s probably one of the best foundations for our economy, job creation, and we’re true believers in that.”

Aside from facilitating commerce, infrastructure investments also often yield jobs and a relatively high return on investment for government spending. Yet funding, both federally and in many states, has suffered in recent years as the gas taxes that largely fund improvements have yielded less and less revenue thanks to better fuel economy and gas alternatives.

Both Seattle and San Francisco are struggling to meet the demands of growing urban and regional populations. And both say they can only address those needs with federal aid, which has become increasingly difficult to secure.

“I think we all realize that the days of porkbarrel projects are gone,” Lee said. “And when you compete, I’m competing with New York, Atlanta, Chicago, everybody else — they’re putting up their best efforts to win these TIGER grants,” provided by the Department of Transportation.

While the conversation among Lee and Murray focused on infrastructure, the pair said the federal government also has a role to play on a range of other priorities, such as homelessness, manufacturing, climate change and trade.

“There’s a whole series of issues where we can incubate it, and we can move it forward, but unless there’s a return to some form of that national urban agenda, and the federal government as our partner, it’s just going to kind of stick and not grow much,” Murray said.