US Capitol file

FILE - In this Sept. 16, 2013, file photo, the U.S. Capitol at sunset in Washington. (AP Photo/J. Scott Applewhite, File)

WASHINGTON — Congress returns to the U.S. Capitol this week, after a five-week recess from the nation's capital, but it's unclear what lawmakers may be able to accomplish before the session ends in December.

The next four months could be a make-or-break period for Congress, as the 2020 presidential contest will eclipse everything else next year.

“This window between now and December is, in a way, the last best window of opportunity for this Congress to do something,” said George Mason University political science professor Jennifer Victor. “That being said, you still have divided government. It just doesn’t seem very hopeful to me.”

Upon the return from the district work period, the Senate has 55 working days left in 2019, while the House has 41.

During the recess, Democrats have largely rallied behind legislation to address gun violence. There have been four mass shootings since Congress left Washington at the start of August, including deadly shootings in El Paso, Texas, and Dayton, Ohio, that took a combined 31 lives. The Democrat-controlled House also is expected to continue its push toward impeachment of President Donald Trump and investigation of his administration.

Those priorities, as well as efforts to pass new environmental laws, will face stiff resistance in the GOP-controlled Senate and are unlikely to go beyond the House floor.

Meanwhile, Republicans, at the urging of the Trump administration, have set out to ratify the United States-Mexico-Canada trade deal by the end of the year, and the Senate still has a slate of Trump judicial nominees to continue vetting.

“I don’t think we should expect any new big legislation,” Victor said.

U.S. Sen. Bill Cassidy, R-Baton Rouge, has been working on priorities that he said could break through the partisan gridlock that has mired Congress this year, including surprise medical bills, prescription drug costs and a long-term re-authorization of the National Flood Insurance Program.

During a recent meeting with this newspaper's editorial board, Cassidy said his background as a charity hospital doctor has driven his push to look for creative patient-focused ways to lower health care costs.

“I think we’re coming to a point where even those on the left are acknowledging the problems," he said.

Cassidy is leading a bipartisan effort to introduce legislation meant to prevent people from facing exorbitant medical bills when they inadvertently receive treatment out of their insurance networks — a frustrating health care issue that affects countless patients each year.

But a group called Doctor Patient Unity has muddied the issue with a campaign during the August recess with television ads and direct mail pieces questioning proposals that have been floated.

Congress must pass a spending plan before the end of the month to prevent a government shutdown. Before the recess, the House and Senate agreed to a framework for the budget. None of the individual bills that make it up has received final passage yet, but the deal that was struck indicates a shutdown will likely be avoided, Victor said.

“That seems to be moving along," she said. “They are able to get done what has to be done.”

Congress also will be tasked this month with some form of extension of the National Flood Insurance Program, which covers nearly half a million Louisiana policyholders. The latest temporary extension of the NFIP — the program's 12th since 2017 — is set to expire at the end of September.

Since taking control of the House in January, House Democrats have set out on an aggressive agenda to pass their priorities on issues like gun control, prescription drug prices and the environment, as well as hold numerous hearings to investigate the Trump administration. House Speaker Nancy Pelosi, D-California, has often decried the GOP-controlled Senate's refusal to take up many of those bills after they've made it through the House.

"But we’re very, very proud of the work that our members have done," Pelosi said during a news conference before the recess.

She repeatedly called on Trump to call the Senate back to Washington to consider House-passed gun legislation following mass shootings during the break. The bills would expand mandatory background checks for gun purchases.

"Leader McConnell, describing himself as the 'grim reaper,' continues to obstruct these bipartisan bills," Pelosi wrote in one letter to Trump during the break.

Trump has offered mixed statements on whether he would support gun legislation. His administration has reportedly been mulling various proposals.

Meanwhile, Republicans in the House, including Minority Whip Steve Scalise, R-Jefferson, have been airing their frustrations over the leadership's priorities of passing legislation that will not pass muster in the Senate.

Speaking recently about a prescription drug bill that received bipartisan support in committee but Democrats altered when it hit the floor, Scalise said it was an example of the partisanship that has mired Congress.

"When it came to the floor, Speaker Pelosi added poison pills to it to make it a partisan bill that had no chance of going anywhere in the Senate," he said. "Instead of all these resolutions and attempts to harass the president, why don't we use the floor time to bring bills to the floor to solve real problems?"

More than a dozen House Republicans have announced their retirements in recent weeks.

“It’s a sign that most House Republicans don’t think they are likely to take the majority in the next election,” Victor said.

Scalise, who has steadily built a national profile since narrowly surviving a mass shooting in 2017 and has eyed the House speaker position in the past, has spent much of the August recess campaigning for GOP candidates in hopes of regaining Republican control over the chamber.

He made stops in Illinois, Missouri, Ohio, Wisconsin, Wyoming, Minnesota, Kentucky, Michigan, Indiana, Pennsylvania, New York, Nebraska, West Virginia, Virginia, and California, according to Scalise's campaign.

Email Elizabeth Crisp at ecrisp@theadvocate.com and follow on Twitter, @elizabethcrisp.