Congress comes back to Washington Monday with a packed agenda — but few common causes between Democratic and Republican lawmakers.

“We’ve got a big fight coming up in Washington — and that is on guns,” warned Senate Minority Leader Chuck Schumer (D-N.Y.) on “The Cats Roundtable” Sunday.

Democrats in both the House and Senate are interested in moving on gun control following the recent mass shootings in Texas and Ohio.

At the top of Schumer’s wish list is a universal background checks bill.

The House passed a background check bill in February with the help of eight House Republicans, but Senate Republicans haven’t touched it.

“Everyone is for it, but [Senate Majority Leader Mitch] McConnell is standing in the way right now,” Schumer said.

In reality, Republicans need political cover from President Trump and they’re not sure if they’ll get it.

“The president needs to step up here and set some guidelines for what he would do,” explained Sen. Roy Blunt (R-Mo.) on Sunday’s “Meet the Press.”

One thing the president could support is a new version of Manchin-Toomey, a bipartisan background check bill, which is in the process of being written and will likely not go as far as the House version.

Sen. Pat Toomey (R-Pa.) told NBC Philadelphia last week that he may need Trump to endorse the bill in order for it to pass.

“Well, if we want the vote to be successful, he might have to do it,” Toomey said. “The president’s going to have a huge influence on how this goes.”

Meanwhile, House Judiciary Committee Chairman Jerrold Nadler (D-N.Y.) is expected to offer a resolution this week that would better define his committee’s impeachment investigation into President Trump as more House Democrats embrace the effort.

Politico reported that draft language could come as early as Monday, with a vote expected Wednesday.

“My sense is, all of the next three months is going to be basically drowned out by an action that’s going to start this week with a vote in the House Judiciary Committee to formally move toward impeachment, not formally begin the impeachment, but move toward it,” said Karl Rove, President George W. Bush’s top political adviser, on “Fox News Sunday.”

House Republicans want Democratic House Speaker Nancy Pelosi to put the United States-Mexico-Canada Agreement that replaces NAFTA on the floor.

“There is strong Republican support for this and many Democrats would like to see this done as well,” a House GOP aide told The Post.

“Beyond that, Pelosi has been promising a drug pricing plan since January and we haven’t seen anything on that; that’s something Republicans would also be interested in working on.”

While the Senate is where Democratic House bills go to die, McConnell plans to keep the upper chamber busy working through Trump’s nominations.

The Senate will also start work on appropriations bills, as the House plans to pass a continuing resolution to fund the government past Sept. 30.

Congress has until Oct. 1 to pass fiscal year 2020 funding bills in order to avoid yet another government shutdown.