President Bush said Thursday that the House Democrats' version of a terrorist-surveillance bill would undermine the nation's security and that if it reaches his desk, he would veto it.

Ratcheting up his rhetoric, Bush said, "The American people understand the stakes in this struggle. They want their children to be safe from terror."

The House is expected to vote on the measure later Thursday.

Congressional sources told FOX News that House Majority Leader Hoyer has agreed to a Republican request that the House go into a secret session to consider the surveillance package.

An aide says: "We will discuss the importance of permanently extending the Protect America Act, the flaws in the Democrats new FISA legislation, and why immediate passage of the bipartisan, Senate-passed FISA bill is the best solution to protect the American people and our Armed Forces around the world."

Closed sessions are extremely rare in the House, although they are more common in the Senate. The House has only moved into closed session five times since 1825. The last time was in 1983 when lawmakers were deabting paramilitary operations in Nicaragua.

Bush went before cameras on the South Lawn before the vote to encourage Democrats to drop their effort and, instead, support a Senate-passed version.

Replying to Bush, Sen. Edward M. Kennedy, D-Mass., said the president was trying to bully Congress and mislead the people.

"He refuses to accept that under our system of government, neither the president nor the telecommunications companies gets to decide which laws to follow and which to ignore," Kennedy said in a written statement.

"The president wants Congress to pretend that his administration did not conduct a massive, illegal, domestic warrantless surveillance program that was one of the most outrageous abuses of executive power in our nation's history. Rather than accuse Congress of playing politics, the president should stop playing politics with our national security," he said.

The law is intended to help the government pursue suspected terrorists by making it easier to eavesdrop on foreign phone calls and e-mails that pass through the United States. The law expired Feb. 16 after Congress did not quickly renew it. Bush opposed a temporary extension and has warned that failure to renew the law would put the nation at greater risk.

Bush said the House bill "could reopen dangerous intelligence gaps by putting in place a cumbersome court approval process that would make it harder to collect intelligence on foreign terrorists."

"Their partisan legislation would extend protections we enjoy as Americans to foreign terrorists overseas," the president said. "It would cause us to lose vital intelligence on terrorist threats, and it is a risk that our country cannot afford to take.

The Senate-passed version would grant legal immunity to the telecommunications firms. Bush said lawsuits against telecommunications companies would lead to the disclosure of state secrets. Further, he said it would undermine the willingness of the private sector to cooperate with the government in trying to track down terrorists.

Directing his message at the House, Bush said, "They should not leave for their Easter recess without getting the Senate bill to my desk." The recess begins Saturday.

He said the Senate would not pass the House version of the bill, and even if the Senate did, he would veto it.

Nineteen Democrats on the House Judiciary Committee issued a statement on Wednesday challenging the administration's arguments.

"We have concluded that the administration has not established a valid and credible case justifying the extraordinary action of Congress enacting blanket retroactive immunity as set forth in the Senate bill," they said in a statement issued by the committee chairman, Rep. John Conyers, D-Mich.

They said they have seen no evidence that lawsuits have harmed the telecommunications companies' reputations or finances, or that intelligence gathering has been compromised.

FOX News' Chad Pergram and Jim Angle contributed to this report.