WASHINGTON - Just when Congress should be zipping through end-of-year work, the House remains closed due to an anthrax scare, and senators are taking early trips to the airport after approving relatively minor bills.

Anthrax was mailed this week to the office of Senate Majority Leader Tom Daschle, D-S.D. And though the number of people exposed to the dangerous bacteria held steady at 31, the precautionary steps Congress took slowed its work to a crawl in the eerily near-vacant Capitol.

All six House and Senate office buildings, three for each chamber, were locked down Thursday so teams of workers could scour them through the weekend for hazardous substances. As of Thursday afternoon, officials said there were still no new discoveries of additional spores of the deadly bacteria beyond Daschle's office in the Hart Senate Office Building.

"This has been a trying time for all of us, and particularly for my office," Daschle said. He said no evidence was found of contamination in the buildings' ventilation systems, as had been feared. But in an interview with NBC News, he said "some additional contamination" had been found in his office.

"By and large, it has been contained to the office and mailroom," Daschle said. Sen. Kent Conrad, D-N.D., said 30 of the 31 people who preliminary tests showed were exposed to bacteria had been present in Daschle's office Monday, when the anthrax-laden letter was opened. The other worked in a Senate mailroom in an adjacent building, Conrad said.

Sen. Bill Frist, R-Tenn., a physician whose colleagues are watching to keep current on developments, reported Thursday on his Web site that none of the hundreds of senators, staff members and others whose nasal passages were swabbed Monday for evidence of exposure were found to have been exposed. Results of those swabbed Tuesday will be available Friday, Frist said, and those swabbed Wednesday will be learn Saturday whether they were exposed.

Amid the tension, the Senate snapped into business Thursday morning and by 96-1 gave final congressional approval to a compromise $10.5 billion measure financing military construction projects. It later voted by voice to expand an existing program that encourages drug companies to test and label their products for use by children, a bill the House still must consider.

Senators decided to work Thursday after determining that to do otherwise would hand a victory to the people who have been mailing envelopes of anthrax to Daschle and others around the country.

"We're getting real work done, I think," said Senate Minority Leader Trent Lott, R-Miss.

House bargainers also accepted a Senate demand to include money-laundering legislation in President Bush's anti-terrorism package, resolving the last major hurdle to a bill that both chambers could vote on next week.

Yet it was hardly a day of heavy legislative lifting, a sentiment shared by some senators themselves.

"I think American democracy is shored up measurably by this vote," Sen. Pat Roberts, R-Kan., joked to reporters after the Senate approved the military construction bill. "You've had tidal waves of confidence sweeping across the prairies even as we speak."

And with their suites in the Senate office buildings off limits, senators gave most of their aides the day off and made do with work space in the Capitol. Many worked in the cloakrooms just off the Senate floor or used unmarked Capitol offices _ called hideaways _ that the 66 most senior senators have.

The day's only roll call vote was over before lunchtime, and with the Senate in recess until Tuesday senators began their weekly pilgrimage to the capital's airports.

Yet the Senate was a beehive of activity compared to the House, whose leaders had sent the chamber home Wednesday afternoon because of the anthrax scare. The contrast between the House's absence and the Senate's presence was still a raw topic on Thursday.

North Dakotan Conrad said the House's departure was unfortunate. "It sends the wrong message," Conrad said. "We should not be frightened."

House Majority Whip Tom DeLay, R-Texas, met with a handful of other House members at Republican Party headquarters to discuss security.

"Congress is not a building. Congress is wherever elected representatives gather to make decisions for the American people," he told reporters, noting that his group was at work.

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On the Net: Sen. Bill Frist's Web site: http://frist.senate.gov/