Congress this week plans to help President Trump uphold his top campaign promise to build a wall along the southern border when it votes on allocating $1.6 billion for the project.

But Democrats are vowing to keep it from becoming law.

The funding will be included in a group of fiscal 2018 spending bills, combined into one measure, that House lawmakers will vote on before leaving for the August recess.

The money would fund "physical barrier construction along the southern border, including bollards and levee improvements," according to the House Appropriations Committee. The funding level would match Trump's fiscal 2018 request.

"The president campaigned across America about making sure our borders are secure," Majority Leader Kevin McCarthy, R-Calif., said when he announced the pending vote. "The American public has requested it."

While the funding is expected to win approval in the GOP-led House, Senate Republicans are more wary of tacking it on to must-pass spending bills that keep the government operating.

"That is going to be a thorny issue on the Senate side," Homeland Security Chairman Michael McCaul, R-Texas, told the Washington Examiner.

Senate Democrats have vowed to oppose any spending bill with border wall funding, calling the provision a "poison pill" that will prompt them to block a final fiscal 2018 spending deal.

"To my Republican friends in the Senate, I'd say persuade your colleagues in the House to abandon this dangerous, irresponsible path they've put us on which can only lead to a government shutdown," said Senate Minority Leader Chuck Schumer, D-N.Y.

A top Senate GOP appropriator, however, says he plans to try to advance border wall funding.

Senate Homeland Security Appropriations Subcommittee Chairman John Boozman, R-Ark., told the Washington Examiner he will include the money in the fiscal 2018 Homeland Security spending bill.

"It's a huge priority for the president," Boozman said. "We are going to work really hard to get it done. Everybody on our side is interested in trying to get it done."

The funding may not make it much further than the Senate committee, however.

Republicans abandoned plans to include border wall funding in the fiscal 2017 spending measure because of Democratic opposition. Despite their minority status, Democrats have considerable leverage because their votes are needed to clear a final spending agreement in both chambers.

Neither House Speaker Paul Ryan, R-Wis., nor Senate Majority Leader Mitch McConnell, R-Ky., are eager to engage in a politically dangerous spending showdown with Democrats. That diminishes the chance of border wall funding making it into a major combined spending deal most lawmakers expect will be needed to fund the government in fiscal 2018.

Senate Majority Whip John Cornyn, R-Texas, called the appropriations route "problematic," because "it gives a convenient target to Democrats" who want to block all border security funding.

But Republicans are carving out a path for the border wall outside of the spending process. McCaul is working with Cornyn on an authorizing bill that would create a new border security plan that incorporates wall funding.

McCaul told the Washington Examiner the border security proposal will be ready for consideration in the House Homeland Security Committee in September.

"It will include physical infrastructure technology and personnel," McCaul said. "We've been working very closely with the Homeland Security secretary on this and we are finalizing language on the bill."

Trump looms over the process. He was angry when Republicans excluded border wall funding at the behest of Democrats in the fiscal 2017 bill, suggesting in a May 2 tweet that "Our country needs a good 'shutdown' in September to fix mess!"

Republicans are now trying to placate Trump, but avoid a government shutdown by angering either Democrats or the president, who also wields a veto pen and could threaten not to sign a spending bill without border wall funds.

"He wants it done," McCaul said.