National Guardsmen began fanning out to airports across the country Friday, adding a layer of security prompted by the Sept. 11 terrorist attacks on New York and Washington.

The largest contingent began arriving before 4 a.m. at Boston's Logan Airport, where terrorists hijacked the two airliners that were crashed into the World Trade Center's Twin Towers.

The armed military police in camouflage were also posted at Newark, N.J., where a third hijacked plane took off, and at airports including Detroit, Minneapolis-St. Paul, Louisville, Ky., Los Angeles International Airport, and all 19 of Florida's commercial airports.

The National Guard presence is a temporary safety measure while Congress debates an aviation security bill.

It was put off until next week after talks stalled Thursday over whether to federalize airport security workers, the remaining issue blocking passage of the bill.

Fissures in the united veneer of D.C. lawmakers seem to have erupted after three weeks of comity on Capitol Hill following the attacks.

Video: Partisanship Re-Emerges in Congress

Members of the Commerce, Science and Transportation Committee are said to solidly back the aviation security bill but the White House is resisting one provision. Aides to Sen. Ernest Hollings, D-S.C., and Sen. John McCain, R-Ariz. — who co-sponsored the bill — say that two meetings with Transportation Secretary Norman Mineta were canceled Thursday, but Senate aides said the Senate leaders were close to a compromise with the White House.

At issue is whether to make airport screeners federal employees.

President Bush has recommended that the current system in which private contractors provide screeners remain unchanged except that the government would take over qualification and training of screeners. 

The Senate bill wants to federalize screeners at the nation's top 142 airports but leave private contractors in smaller airports. 

Sources from both the majority and minority offices said at one point, the White House seemed "ready to cave" and agree to a proposal in the bill calling for "partial federalization."

But the House too busted chances of an agreement after House members -- including Rep. Tom DeLay, R-Texas -- read the language proposed by the bill's co-sponsor Hollings and found it to be unacceptable.  House Republican leaders indicated they would rather abandon the effort to pass legislation and instead let the president impose new security requirements by executive order.

Opponents of federalizing contend it would create an unwanted new federal bureaucracy. Supporters of federalization say airports now contract security to the lowest bidder, which results in poorly paid, poorly trained screeners with high turnover rates.

Senate Majority Leader Tom Daschle, D-S.D., said Thursday that security must be in the hands of professionals because "you don't professionalize if you don't federalize."

But Senate Minority Leader Trent Lott, R-Miss., disagreed.  "There are those who say let's just take over the current system.  To me that is very unattractive because the current system is not working."

McCain warned that delay in passing the bill will likely prolong the reluctance of many Americans to get back on airplanes. 

Better security "will be the major step in restoring the financial viability not only of the airlines but of America," McCain said.

The Senate bill calls for enabling the Transportation Department to deploy air marshals on all flights, requiring Federal Aviation Administration action to prevent unauthorized entry into cockpits, and stipulating new anti-hijacking training for flight and cabin crews.

It also authorizes a passenger fee in the $1.50 to $2.50 range per one-way flight to help pay the costs of increased security.

The parties agreed that for transition should take place within 18 months to avoid a too-rapid shift that could undermine security.

Meanwhile, lawmakers are considering other incentives to persuade Americans to leave home and boost the travel and tourism industry.

Legislation has been introduced for a $500 per person tax credit for personal travel expenses. 

Julie Asher and the Associated Press contributed to this report.