WASHINGTON (Reuters) - Republicans in the U.S. Congress, unable so far to resolve deep disagreements over spending for the fiscal year starting on Oct. 1, are mulling whether to seek a bipartisan budget deal with Democrats similar to one reached nearly four years ago.

Speaker of the House Paul Ryan introduces his new tax policy at the National Association of Manufacturers Summit in Washington, U.S., June 20, 2017. REUTERS/Aaron P. Bernstein

With only 20 working days to go before a lengthy August recess, some Republican lawmakers say a bipartisan agreement could help clear a legislative schedule crammed with other top priorities, including a separate budget resolution, tax reform, infrastructure and an increase in the federal debt limit.

In December 2013, Republican Representative Paul Ryan, now speaker of the House of Representatives, and Democratic Senator Patty Murray worked out a two-year deal that canceled some spending cuts in fiscal 2014 and 2015 in return for some longer-term spending reductions. The Ryan-Murray agreement was promptly enacted into law.

A bipartisan deal could avert a restrictive spending plan that would cap funding for U.S. agencies and a government shutdown threatened by President Donald Trump.

“I think what we need is another Ryan-Murray sort of proposal,” said Republican Representative Mike Simpson, a senior member of the House of Representatives’ Appropriations Committee, which is in charge of writing annual spending bills.

Speaking to reporters after a House Republican meeting, Simpson said the idea was in the early stages.

Republicans, who control the House and Senate, have lashed out at deep spending cuts that Trump has proposed. But they are divided over how much top-line spending should be appropriated next year, including for a military buildup Trump wants.

A bipartisan negotiation is just one of several options. Another would rush one massive spending bill for fiscal 2018 through the House in July, instead of the dozen separate appropriations bills that Congress tries to write every year.

Doing so would allow Republicans to tout an accomplishment to their constituents in August during a year that has so far seen few legislative achievements.

Given the limited time to write such a bill, Ryan might have to resort to just passing a “national security” spending bill that would fund the military and other security activities.

Some Republicans want to boost military spending to $640 billion, which would require deep cuts to non-defense programs that are popular among Republican moderates.

Congress must also pass a budget resolution to facilitate tax reform legislation. The House Budget Committee hopes to mark up such a measure before June 30, panel members said.