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The House of Representatives heeded President Bush's call Friday and passed an amendment to the homeland security bill that gives the president the flexibility he has demanded in hiring, transferring and firing non-performing employees.

The 229-201 vote for the amendment states that union collective bargaining rights must apply to workers already covered by union agreements as they move into the new agency, but the president can waive those rights, in writing, during times of national emergency. That is a slightly higher threshold for waiver than the president has under current law for other departments.

"We believe this approach represents a sensible and reasonable compromise," said Rep. Christopher Shays, D-Conn., who sponsored the amendment.

President Bush said Friday that he would have no choice but to veto the homeland security bill if it did not grant him executive power to hire, fire and transfer employees.

"The bill doesn't have enough managerial flexibility as far as I am concerned," said the president at an early-morning press conference, stating that he wants to "allow future senators and future members of the House and a future president to say, 'I can better protect the homeland thanks to what was done in the year 2002.'"

But opponents of the measures say that the amendment denies employees union rights that other federal workers receive.

"This amendment provides the president with a trap door to deny union membership," said Rep. Steny Hoyer, D-Md.

The House's vote on the homeland security bill is one of the last acts it will complete before leaving for August recess. The Senate is in session for another week, and planned to vote sometime in the next week.

"We need this department for one main reason," Bush said in the Friday-morning address at the Eisenhower Executive Office Building. "America needs a group of dedicated professionals to wake up each morning with the overriding duty of protecting the American people."

But as the president complimented Congress for working in a quick and bipartisan manner, he indicated that he would have no choice but to veto the measure if it limits his leeway to manage the proposed department's personnel.

"I appreciate the work of Sen. Lieberman," Bush said of the Connecticut Democrat who is shepherding the bill through the Senate. "I am concerned, however, the way the committee has passed out the homeland security bill."

"I am not going to accept legislation that limits or weakens the president's well-established authorities, authorities to exempt parts of government from federal labor-management statutes when it serves our national interests," Bush said Friday.

As Bush traveled to North Carolina to discuss medical malpractice Thursday, the White House warned that the crucial flexibilities included giving the president the abilities to move ineffective employees out of the agency and transfer up to 5 percent of the agency's budget to more urgent security programs.

"The president is very concerned that the substance of the Senate's proposal so far on homeland security is a step backward, not forward, in protecting the country," White House spokesman Ari Fleischer told reporters traveling with the president. "The president remains hopeful and optimistic that these provisions can be fixed without a veto. But he does feel strongly about it."

"He will receive a recommendation from his advisers to veto this if the president's concerns are not addressed," Fleischer added.

The president also opposes requiring Senate confirmation for his assistant on homeland security issues, currently former Pennsylvania Gov. Tom Ridge.

A Cabinet-level Department of Homeland Security would take 170,000 employees from 22 agencies and put them under an umbrella department responsible for securing the homeland and receiving intelligence.

The department will have four purposes: handling border and transportation security, coordinating activities with local and state first responders, harnessing technologies to provide effective counter-terror strategies and assessing and act on threats to the homeland.

Lawmakers in both chambers have added as many as 100 amendments to each version of the bill and debate continues over whether to include the Secret Service, U.S. Customs Service, Coast Guard and Federal Emergency Management Agency into the new bureau.

One key Democrat expressed surprise and disbelief Thursday at the White House's veto threat.

"Eighty-five to ninety percent of the bill our committee is going to be approved, is agreed on by the White House," said Sen. Joe Lieberman, D-Conn., chairman of the Senate Governmental Affairs Committee. "I can't believe frankly that the president would veto the bill over this."

Unions representing many federal workers contend Bush already has all the power he needs and is just trying to circumvent civil-service protections.

Ridge reiterated that the urgency of homeland security necessitates getting rid of underperforming bureaucrats.

"I think the president ... would like to review the notion of how you deal with non-performing people," the homeland security chief said. "We are at war. These are our soldiers. ... It's really about trying to get the best people in the right place at the right time in order to enhance our security for this country."

Fox News' Jim Angle and James Rosen contributed to this report.