WASHINGTON- U.S. senators said they expect to see final text on Sunday for a sweeping $1 trillion package for roads, rail lines and other infrastructure, predicting final passage later this week.

Senator Susan Collins, a Republican from Maine, told CNN that she believes at least 10 Republicans will support the measure, enabling it to easily clear procedural hurdles.

"My hope is that we'll finish the bill by the end of the week," Collins said, adding that the measure is "good for America."

The Senate is expected to convene at 12:00 noon EDT (1600 GMT) on Sunday in a rare weekend session.

A sizeable bipartisan majority in the closely divided Senate has backed the bill in two procedural votes, although no lawmakers have seen the final text. Senate votes so far have been on a shell bill that will incorporate the actual legislation once it is complete. 

On Friday, the Senate voted 66-28 to take up the bill with 16 Republicans joining all 48 Democrats and two independents. The Senate also convened a rare session on Saturday.

Senator Joe Manchin, a West Virginia Democrat, told CNN that the infrastructure bill should win strong support. But, he said he could not guarantee that a companion, $3.5 trillion 'reconciliation' spending bill can pass with the support of only Democrats, as it needs to be fully paid for.

Senate Democrats would need every vote in their party to pass the measure under special budget rules that allow for a simple majority - including Manchin's.

"Both of these bills should go up on their own merits," he said.

The massive infrastructure package is President Joe Biden's top legislative priority.

In addition to $450 billion that had previously been approved, the package is expected to include $550 billion in new spending and will dramatically ramp up the country's expenditures on roads, bridges, transit and airports. It also includes money for scrapping lead water pipes and constructing electric vehicle charging stations.

Supporters, including Democratic Senate leader Chuck Schumer and Republican Senate leader Mitch McConnell, have been optimistic about the bill's chances of becoming law.

(Reporting by David Morgan and Richard Cowan; Writing by Makini Brice; Editing by Edmund Klamann, Ross Colvin and Andrea Ricci) ((M.Brice@thomsonreuters.com;))