WASHINGTON — Congress went on recess with plenty of homework waiting when it gets back, chiefly how to resolve partisan problems that threaten to upend the appropriations process in the House and a thorny amendment to the Senate defense authorization bill.

With an abbreviated election year calendar, tough fights make it more likely Congress will deadlock and head to a continuing resolution to fund the government, a lamentable and all-too-familiar scenario for Pentagon budgeteers. Congress has less time for legislative action before federal funding ends with the fiscal year on Sept. 30 — with a seven-week recess and only three weeks of dual sessions between the Memorial Day and Labor Day recesses.

"I think it's going to be extremely difficult to get any appropriations bill done," said Jim Moran, a former Democratic congressman from Virginia who served for many years on the House Appropriations Committee. He is a a defense lobbyist at the law firm McDermott Will & Emery in Washington.

In the House, partisan divisions over an amendment to prohibit federal contractors from discriminating on the basis of sexual orientation or gender identity derailed a 2017 energy-water appropriations bill. After the amendment was added to the bill, the bill failed on a 305-112 vote that saw House Democrats calling "Shame! Shame!" as some Republicans changed their votes to block their own bill.

Beyond that fight, there are significant differences between the otherwise-popular military construction-Veterans Affairs appropriations bills in the House and Senate, which the two chambers' appropriations committees must still resolve in conference.

"If the easiest one to pass still has a lot of hurdles, I don't see any way to avoid a continuing resolution that will take us past the election, at least into December," Moran said.

Though House Speaker Paul Ryan, R-Wis., has pledged regular order, meaning more openness to lawmakers' amendments, he has since that vote suggested to reporters that procedure may be modified for the sake of convenience — saying the Democrats' goal with the LGBT amendment was "sabotage."

With 12 appropriations bills for Congress to consider, the anti-discrimination measure's sponsor, New York Democrat Sean Maloney, told the Washington Post he plans to keep trying to get the amendment passed. The issue is a potent one for Democrats; House Democratic Whip Steny Hoyer, in an emailed message May 27, signaled he does not plan to let the matter drop.

Compounding the issue is Congress' 2011 ban on earmarks, which gives lawmakers less reason to vote for appropriations bills than ever. "Certainly if you're opposed to government spending, which most Republicans are, the only way you can get political credit is to vote against it," Moran said. "Without earmarks, you can't go home and say, 'I voted for the bill, but look at this new school or road.'"

One option for Ryan is to exercise a firmer hand through the House Rules Committee to guard against poison pill amendments coming to the floor. The gamble there is that Democrats and the Republican Party's right flank might vote together to buck a closed rule and thwart such a move.

"We've tried open rules for 20 years, but the process has broken down, and the way to get it moving again is to give more power to the Rules Committee …but it's going to make Democrats and Republicans upset,"  Moran said. "Ryan is going to have to work with the Senate leadership to use similar tactics. That's the only way to get this done."

In the Senate, the 2017 National Defense Authorization Act is set for a floor debate — as Armed Services Chairman John McCain has introduced an amendment that would add $18 billion. The move differs from the approach for House appropriations and authorization, which hew to the president's top-line for defense, but shift money in the wartime overseas contingency operations (OCO) budget for base budget needs.

McCain's proposed amendment adds OCO funding for troops, aircraft, ships and tanks, among other items left out of President Obama's 2017 budget request — though Congress-watchers rate its chances of passage as low.

For aircraft, the measure adds authorization for $1 billion in Army rotorcraft procurement, $1.2 billion for 14 additional F/A-18E/F Super Hornets and $1.5 billion to buy 11 F-35 Lightning II jets across the services. There is $452 million for C-130Js for the Air Force and $158 million for two KC-130J Super Hercules tankers for the Marine Corps. The Marines would also get $150 million to buy two MV-22 Ospreys.

Under the auspices of the European Reassurance Initiative, there is $172 million to modernize 14 M1 Abrams tanks and another $73 million for 14 M2 Bradley Fighting Vehicles.

The bill would add $2.4 billion to increase troop levels, and $300 million to increase the planned military pay raise from 1.6 percent to 2.1 percent.

For allies, McCain would add $800 million to the Afghanistan Security Forces Fund, $200 million for Iraqi forces fighting the Islamic State group,  and $150 million to bolster Ukrainian security. He adds $200 million for allies in the Mideast and Europe to stockpile precision munitions and $200 million to the Kurdish peshmerga stipend.

"It's kind of a moot issue," Moran said. "In the Senate you could probably get agreement on that, but in the House it would be impossible."

On May 26, the Senate Armed Service Committee's top Democrat, Jack Reed of Rhode Island, said there was "serious discussion going on right now" among Senate Democrats, "about what's the best approach."

"Overarching all of this is the arrangement we worked out last year, which is that defense spending and domestic spending would increase at the same rate or stay at the same rate," Reed said. "That's the other part of the discussion: What do we do to ensure that goal is achieved?"

Dick Durbin of Illinois, the chamber's No. 2 Democrat and ranking member of the Senate Appropriations defense subcommittee similarly told reporters that Democratic support for McCain's amendment "depends on whether there is an equal amount for nondefense."

"I see it as unanimous thinking," among Senate Democrats, Durbin told reporters May 26.

The Senate Appropriations Committee's ranking Democrat, Sen. Barbara Mikulski of Maryland, said explicitly that McCain's amendment without an equal hike for domestic spending would contravene the hard-fought 2015 Bipartisan Budget Act.

"We have the budget act and we're supposed to live by the budget act, and the budget act is not only for appropriations but every bill within the United States Senate, so that's one thing," Mikulski told Defense News. "If [McCain] wants to go outside of it by going to [more] OCO, there has to be additional parity for Democrats."

Twitter: @ReporterJoe