WASHINGTON (Reuters) – Republicans in the U.S. Congress are blocking emergency funding for Ukraine and threatening to force a government shutdown in an effort to tighten security along the U.S.-Mexico border.

Why Are Republicans Focusing on Border Security?

Record numbers of migrants have been caught illegally crossing the border since Democratic President Joe Biden took office in 2021.

The U.S. Border Patrol arrested about 2 million migrants at the U.S.-Mexico border in fiscal year 2023, similar to record-breaking totals during Mr. Biden’s first two years in office.

During Republican Donald Trump’s 2017-2021 presidency, migrant arrests peaked at 852,000 in fiscal year 2019.

Republicans say Mr. Biden has encouraged migrants by loosening Trump-era restrictions. They also oppose new Biden policies that allow certain migrants to enter legally for humanitarian reasons, saying they circumvent standard immigration channels.

Immigration is a top concern for conservative voters ahead of the November 5 elections that will decide control of the White House and Congress. Mr. Biden is seeking a second term and Mr. Trump is the leading candidate for his party’s nomination.

What Do Republicans Want at the Border?

Mike Johnson, the Republican House speaker, has said Mr. Biden needs to reinstate Trump-era policies and crack down on border crossings.

Mr. Johnson also has called on the Democratic-led Senate to approve a bill passed by the House in May that would effectively end access to asylum at the border.

The measure, known as H.R. 2, passed with broad Republican support but with no backing from Democrats. The bill has not come to a vote in the Senate, where it would face steep Democratic opposition.

The White House has said Mr. Biden would veto the bill.

What Is in the Republican Border Bill?

The bill generally bars migrants from seeking U.S. asylum at the border if they passed through another country en route to the United States, one of several provisions that would greatly reduce such claims.

It grants the U.S. homeland security secretary sweeping authority to suspend entry to migrants to maintain “operational control” of the border, a standard that would prevent all illegal entries.

It mandates construction of at least 900 miles of border wall, a signature Trump policy. It would end new Biden “parole” programs that have allowed hundreds of thousands of migrants to enter legally, including Ukrainians and Afghans.

The bill would require families to be detained if a parent was charged with illegal entry, and make it easier to quickly return unaccompanied children to their home countries.

What Do Democrats Want?

A White House funding request pairs tens of billions of dollars for Ukraine and Israel with nearly $14 billion for U.S. border security.

That money would pay for 1,300 additional U.S. Border Patrol agents, 1,600 new asylum officers and 375 new judge teams.

The package has been blocked by Republicans in the Senate.

House Speaker Johnson’s office says the bulk of the money would be used to manage border arrivals, instead of discouraging illegal immigration.

Is There Room for Compromise?

A bipartisan group of senators has been talking for months about a possible deal.

The core negotiators—Democrat Chris Murphy, Republican James Lankford and independent Kyrsten Sinema—have not said what the bill would include, but some details have emerged.

Reuters reported in December that the White House was open to new restrictions on who can seek U.S. asylum and expanding deportation authority.

Among the provisions on the table are heightening the standard for initial asylum screenings and expanding a fast-track deportation process known as “expedited removal.”

Lawmakers have also discussed the creation of a broad expulsion authority similar to the COVID-era Title 42 policy that would allow the U.S. to send migrants back to Mexico or other countries.

The willingness to consider new border restrictions marks a shift from past battles when Democrats focused on winning citizenship for some immigrants living in the U.S. illegally.

Some Democrats, including a coalition of Hispanic lawmakers and immigrant advocates oppose reducing access to asylum at the border and have urged Mr. Biden to reject such proposals.

What’s Next?

Lawmakers must pass spending bills by January 19 and February 2 to avoid a partial U.S. government shutdown. Some Republicans say any spending legislation must include H.R. 2 or other language that will prevent migrants from being released into the United States.

It is unclear whether they will force a shutdown over the issue.

Negotiations are complicated by a House Republican effort to impeach Mr. Biden’s top border official, Homeland Security Secretary Alejandro Mayorkas, for allegedly encouraging illegal immigration with overly permissive policies.