NEW YORK (Reuters) - President Joe Biden's administration heaped pressure on U.S. port employers to raise their offer to secure a labor deal with dockworkers on strike for a second day on Wednesday, choking half the country's ocean shipping.

The strike by the International Longshoremen's Association (ILA) union has blocked everything from food to automobile shipments across dozens of ports from Maine to Texas in a disruption analysts warn will cost the economy billions of dollars a day.

More than 38 container vessels were already backed up at U.S. ports by Tuesday, compared with just three on Sunday before the strike, according to Everstream Analytics.

"Foreign ocean carriers have made record profits since the pandemic, when Longshoremen put themselves at risk to keep ports open. It's time those ocean carriers offered a strong and fair contract that reflects ILA workers' contribution to our economy and to their record profits," Biden said in a post on X late on Tuesday.

He directed his team to monitor for potential price gouging activity that benefits foreign ocean carriers, the White House said.

The ILA, which represents 45,000 port workers, launched its strike just after midnight on Tuesday after negotiations with the United States Maritime Alliance (USMX) for a new six-year contract collapsed.

USMX had offered the union a 50% wage hike, but the ILA's fiery leader, Harold Daggett said the union is pushing for more, including a $5 per hour raise for each year of the new six-year contract and an end to port automation projects that threaten union jobs.

"We are prepared to fight as long as necessary, to stay out on strike for whatever period of time it takes, to get the wages and protections against automation our ILA members deserve," Daggett said on Tuesday.

Hundreds of dockworkers demonstrated at a New York City area shipping terminal in Elizabeth, New Jersey, on Tuesday carrying signs and shouting slogans like "ILA all the way!" as music blared and vendors hawked food.

Trump on Tuesday blamed the strike on inflation, which he said was caused by the Biden-Harris administration.

"Everybody understands the dockworkers because they were decimated by this inflation, just like everybody else in our country and beyond," Fox News Digital quoted Trump as saying in an interview.

"DEVASTATING CONSEQUENCES"

The strike, the ILA's first major stoppage since 1977, is worrying businesses that rely on ocean shipping to export their wares or secure crucial imports. It affects 36 ports - including New York, Baltimore and Houston - that handle a range of containerized goods from bananas to clothing to cars.

The walkout could cost the American economy roughly $5 billion a day, JP Morgan analysts estimate.

The National Retail Federation called on Biden's administration to use its federal authority to halt the strike, saying the walkout could have "devastating consequences" for the economy.

Republicans, including Virginia Governor Glenn Youngkin, also called on Biden to end the strike, warning of its impact on the economy.

Biden has repeatedly said he will not do so.

The U.S. Department of Agriculture said on Tuesday it does not expect significant changes to food prices or availability in the near term.

And retailers accounting for about half of all container shipping volume said they have been busily implementing backup plans to minimize the impact of the strike as they head into the winter holiday sales season.

(Additional reporting by Gursimran Kaur, Nilutpal Timsina, Shivani Tanna and Shubham Kalia in Bengaluru and David Shepardson in Washington; Writing by Richard Valdmanis; Editing by Sonali Paul)