WASHINGTON, April 5 (Reuters) - President Joe Biden will visit Baltimore on Friday to survey the site of a collapsed bridge and meet families of the six construction workers who died, amid growing tensions in the U.S. Congress over using federal dollars to rebuild the bridge.

A cargo ship crashed into the Francis Scott Key Bridge on March 26, sending it collapsing into the harbor. Work to clear the wreckage and restore traffic through the shipping channel is ongoing.

Biden's visit, which will include an aerial tour, comes as state and federal officials have raised alarms over the potential economic hardships that the port's closure could have on the regional economy.

The Port of Baltimore ranks first in the United States for the volume it handles of autos and light trucks and farm and construction machinery, according to the state of Maryland. Most of that traffic has been suspended since the accident, though some terminal operations outside the affected area have resumed.

There are growing signs of friction among some U.S. lawmakers about using new federal dollars to fund the bridge's reconstruction.

Federal officials have told Maryland lawmakers the final cost of rebuilding the bridge could soar to at least $2 billion.

On Friday, the White House's Office of Management & Budget (OMB) sent a letter to Congress asking the federal government to cover all costs to replace the bridge.

The incident has already idled thousands of port workers who depend on it for jobs.

Top White House officials such as chief of staff Jeff Zients, senior adviser Tom Perez and economic adviser Lael Brainard have called large employers in the Baltimore area to encourage them to retain workers, a White House official said.

Local employers, including United Parcel Service, Amazon.com, Home Depot and Mercedes-Benz are committing to retain their workers, the White House said.

The Small Business Administration has also made low-interest disaster loans available, and Biden's supply chain task force has met several times to analyze the impact, "which has so far been manageable," the official said.

The six victims of the bridge collapse were all immigrants from Mexico and Central America, who were fixing potholes on the road surface of the bridge when it collapsed. Four of the bodies have still not been recovered, but all are presumed dead.

Biden's meeting with the families of these immigrant workers comes at a time when Republican presidential nominee Donald Trump has ramped up anti-immigrant rhetoric, casting migrants as dangerous criminals "poisoning the blood" of America, as he seeks the White House a third time.

FUNDING FOR THE BRIDGE

Hours after the bridge collapse, Biden said the federal government would "pay the entire cost" of reconstruction. Last week, his administration announced $60 million in emergency relief.

To fully replace the bridge, Congress would need to approve funding. The administration will pursue all avenues to recover costs and "ensure that any compensation for damages or insurance proceeds collected will reduce costs for the American people," OMB Director Shalanda Young said in her letter.

White House officials have held talks in recent weeks with House of Representatives Speaker Mike Johnson's office over billions in aid for Ukraine and Israel to money for the collapsed Baltimore bridge, said two officials familiar with conversations, who did not wish to be named.

The spending measures separately have bipartisan support, but the White House is aware that Johnson has to satisfy Republican hardliners who oppose the use of federal dollars.

As a result, many of these spending proposals will be tethered together to get across the finish line, the officials said.

A separate congressional source said it is not certain that an emergency supplemental spending bill is necessary while another source said a supplemental bill might not be Baltimore-centric, but general money for whatever disasters have to be met nationwide in the months to come.

In legal filings in federal court, attorneys for the companies that own and manage the container ship that crashed into the bridge said they were not to blame for what happened but did not indicate who they believe is responsible.

They asked a judge to excuse them from any liability for the disaster or, alternately, cap damages at $43 million, the cost of the vessel minus damage and salvage.

(Reporting by Nandita Bose in Washington, Additional reporting by Jarrett Renshaw, Rick Cowan and Daniel Trotta; Editing by Mary Milliken and Sonali Paul)