UPDATE 1-U.S. Senate plans to vote on spending, debt limit deal on Thursday -Rubio

-Rubio@ (Adds Republican senators' comments on potentially difficult vote ahead)

WASHINGTON, July 31 (Reuters) - The U.S. Senate on Thursday aims to pass legislation backed by President Donald Trump that would suspend the federal government's borrowing limits for two years and set spending levels for numerous federal programs through September 2021, Republican Senator Marco Rubio said on Wednesday.

The legislation has already been passed by the House of Representatives and would be sent to Trump for signing into law if the Senate passes it.

Rubio, who said he will vote against the bill, spoke to reporters after leaving a closed meeting where it was discussed. Several other Republican senators who left the meeting said they expected the budget vote to come by mid-afternoon on Thursday.

But some raised questions about whether there was enough Republican support to get the bill over the finish line because of the measure's lack of any deficit-reduction provisions.

"I get the sense that maybe it's closer than they (Republican leaders) want it to be," Rubio told reporters. "I don't see panic. I see caution but not panic."

Senator Mike Rounds, who plans to support the legislation, said Republicans were nervous about the vote. While he said senators were being advised that its fate was likely to be decided on Thursday, Rounds told Reuters, "It's going to depend on whether or not we have the votes" for passage by Thursday. (Reporting by Richard Cowan editing by G Crosse and Leslie Adler)