The top Senate leader on Tuesday announced a deal to authorize funding for federal highway projects for the next six years.

Senate Majority Leader Mitch McConnell, R-Ky., said an agreement has been reached with Democrats on a long-term bill to pay for surface transportation projects. It comes just days away from a July 31 deadline.

"This is a six-year highway authorization that will allow planning for important long-term projects around the country, and the bill provides three years of guaranteed funding for the highway trust fund," McConnell said.

A long-term highway bill as eluded Congress for years now, as the two parties have been unable to agree on how to pay for it. Some Democrats have proposed higher gas taxes, an idea Republicans have said is a non-starter.

As of early Tuesday afternoon, McConnell's office had yet to make public any details of how the bill would be funded.

The House earlier this month passed a five-month financing patch, one of a succession of short-term deals that Congress has used over the years to keep highway projects funded.

McConnell said he struck the deal with Sen. Barbara Boxer, D-Calif., the ranking member on the Senate Environment and Public Works Committee.