WASHINGTON — The coronavirus pandemic is boosting momentum for major broadband legislation, highlighting the widespread lack of high-speed internet in U.S. homes at a time when it has become more essential than ever.

Leading lawmakers of both parties say the long-delayed issue of closing the so-called digital divide is gaining new prominence, as Washington weighs initiatives to help speed economic recovery and improve U.S. competitiveness.

“Having affordable broadband—it’s not a luxury, it’s a necessity,” said Rep. Mike Doyle (D., Pa.), chairman of the House communications and technology subcommittee. “Broadband infrastructure has to be one of the key elements to that, and this pandemic has brought that right to the forefront.”

House Democrats are likely to lead the legislative push for expanded broadband in coming weeks. But many Senate Republicans also are keenly interested, and say the pandemic is underscoring the need for action.

“It helps us drive the point home as to urgency,” said Sen. Roger Wicker (R., Miss.), the chairman of the powerful Senate Commerce Committee. “Absolutely it gives us an impetus—that is one of the silver linings here.”

The issue of accelerating access to home broadband has been stalled for years in Congress. That is largely because of the huge costs involved in serving many remote regions, and lack of agreement on funding sources.

But now, there is new impetus as Americans shelter at home, forcing them to flock online to work, apply for new jobs and obtain a variety of vital services ranging from small-business loans, unemployment benefits and IRS payments to school classes and telemedicine.

A new report from the Federal Communications Commission, set to be released soon, is expected to say the number of Americans lacking access to high-speed broadband declined by more than 14% in 2018. But some advocates have questioned government estimates, saying government data overstates by millions the number of people who have broadband access.

Many millions more have broadband access but can’t afford the service, survey data shows. Soaring use of smartphones has also given many people an excuse not to buy home broadband service, particularly in urban and suburban areas with good wireless coverage.

Despite lofty promises of universal broadband service by federal officials over the past decade, current government subsidies to encourage expansion of broadband networks to hard-to-serve areas and to the poor are sometimes criticized as inefficient and inadequate.

The biggest existing program, the Universal Service Fund administered by the FCC, is funded by fees charged largely on telecommunications services such as long-distance calls. But rising demand for the funds is helping push fees for the Universal Service Fund to more than 21% for the first quarter of 2020, up from about 5.5% 20 years ago, straining the system.

“Our nation’s universal service system had its last grand rehab in 1996. The world is a little different,” said FCC Commissioner Jessica Rosenworcel, a Democrat who has clashed with the commission’s Republican majority over how to modernize the program.

FCC Chairman Ajit Pai, a Republican, defended the agency’s record under his leadership. Mr. Pai noted that he grew up in rural Kansas and has a “deep commitment” to expanding broadband access, including by modernizing regulations governing the program. He said that between 2016 and 2018, the number of Americans without access to high-speed home broadband fell by 30%, while the number of homes with access to high-speed fiber-optic lines also has increased rapidly in recent years.

Meanwhile, the coronavirus outbreak is underscoring the gulf between those communities that have broadband and those that don’t.

“The urgency of this issue is like triple times what it has been,” said Sen. Shelley Moore Capito (R., W.Va.), who co-chairs the Senate Broadband Caucus. Under existing federal programs to subsidize broadband, “we’re getting there, but it’s too damn slow…It could happen in a stimulus bill.”

Sen. Capito said she hears frequently about the problem from physicians in her mountainous state who often are unable to use telemedicine because of patients’ lack of access.

Many students and school systems in the U.S. have been unable to use remote-learning programs during the long school shutdown. That is highlighting the so-called “homework gap” between have and have-not communities.

In Hartford Central School District in upstate New York, fewer than half of the families have access to high-speed internet, Superintendent Andrew Cook said. Even in the district’s main town, high-speed cables don’t run down every street, he said.

With schools closed, teachers are calling students by phone when needed, and the district is distributing paper assignments. “My biggest concern is when we come back next year, what that gap of learning is going to be,” Mr. Cook said.

In late March, President Trump and House Speaker Nancy Pelosi both said they would push infrastructure legislation, including major broadband components, as part of the coronavirus recovery. But attention quickly shifted to a shorter-term effort to shore up small-business lending and other immediate health-care and recovery efforts.

As a result, the effort to advance a broadband infrastructure package is still coming together. It also faces multiple pitfalls, politics being perhaps the biggest.

Already, some Republicans worry Democrats will seek ambitious new environmental or election-reform initiatives in pandemic-related legislation. They privately question whether Democrats want to give President Trump a big legislative win on infrastructure ahead of the 2020 election.

Democrats for their part worry that conservative Republicans will balk at spending more federal money on new broadband and other infrastructure initiatives, as they have in the past.

It remains to be seen how much the pandemic will tip the political scales.

“I know there is a great deal of interest among Republicans and Democrats in taking a small portion of the funds in the next phase” for broadband, said Sen. Wicker. He added, “The president is talking about a Phase 4 [of legislation] and Republicans and Democrats are talking infrastructure as a part of that. I do not think it will be enacted without a broadband component.”