WASHINGTON, Aug 1 (Reuters) - U.S. senators introduced a sweeping $1-trillion bipartisan plan to invest in roads, bridges, ports, high-speed internet and other infrastructure, with some predicting the chamber could pass this week the largest public works legislation in decades.

The massive infrastructure package, a goal that has eluded Congress for years, is a top legislative priority for Democratic President Joe Biden, who billed it on Sunday as the largest such investment in a century.

Senators said the 2,702-page bill included $550 billion in new spending over five years for items such as roads, rail, electric vehicle charging stations and replacing lead water pipes on top of $450 billion in previously approved funds.

"I believe we can quickly process relevant amendments and pass this bill in days," Senate Majority Leader Chuck Schumer, a New York Democrat, said of the legislation after it was announced by a bipartisan group of senators.

"This is a really important bill because it takes our big, aging and outdated infrastructure in this country and modernizes it. That’s good for everybody," said Sen. Rob Portman, the lead Republican negotiator.

Newsletter signup for email alerts

However, some Republicans criticized the bill as too costly.

"I’ve got real concerns with this bill," Republican Sen. Mike Lee said in a floor speech. "All is not well with the way we spend money."

It was not yet clear whether senators outside the bipartisan group that negotiated the bill will offer amendments that could possibly upset the delicate coalition that was cobbled together.

If the bill passes the Senate, it must be considered in the House of Representatives, where some Democrats have blasted it as too small and the Democratic leadership has paired it with a $3.5 trillion "human infrastructure" bill to pour money into education, child care, climate change and other priorities.

Democrats want to offset that social spending with tax hikes on corporations and wealthy Americans earning more than $400,000 a year, measures opposed by Republicans, leaving the fate of both bills up in the air.

Sunday night's developments capped months of negotiating, and infighting, among several groups of senators and the White House.

Initially, Biden said he was seeking about $2 trillion in a bipartisan bill, an amount that Republicans rejected as wasteful and unnecessary.

A group of Republican senators then worked on a plan to spend far less, an effort that eventually died, raising questions if Congress could fashion a deal allowing the Democratic president to fulfill his Jan. 20 inauguration promise of working cooperatively with Republicans.

A bipartisan group of senators, led by Arizona Democrat Kyrsten Sinema, a moderate, and the conservative Portman toiled for months, adding input from House centrists, on a new plan closer to what Biden would accept.

Late in June the group said it had reached a $1.2-trillion deal, but filling in details took more than a month.

With prodding from Schumer and Biden, the negotiators put their staffs to work, nearly around-the-clock, culminating in Sunday's final deal.

(Reporting by David Morgan and Richard Cowan; Additional reporting by Michael Martina; Writing by David Lawder and Arshad Mohammed; Editing by Diane Craft and Clarence Fernandez)