Bartlett, who missed three of 633 roll call votes in 1997, said he did not recall missing those votes. One was to approve the House journal in April; one was an Oct. 30 vote on a nuclear waste amendment; one was a vote on the 2000 Census.
All were lopsided margins.
"Fortunately, my vote wouldn't have made a difference," he said.
At 91.9 percent of 298 roll call votes, Mikulski had the lowest voting attendance rate in the Senate. Bartlett took a jab at Mikulski, who is up for re-election this year.
"She needs an opponent to make that claim, doesn't she?" he said.
But Mikulski aide Rich Fiesta said the senator takes her responsibility seriously and noted that her voting attendance is "well over" 95 percent for her entire career.
"Voting is obviously very important to her," he said.
Fiesta said most of the votes Mikulski missed occurred in July when she was on an important foreign-policy mission in Europe. She was part of a Senate delegation that went to Madrid to participate in negotiations over the expansion of NATO, he said.
Mikulski continued on to Poland, which had applied for membership in the Western alliance. Fiesta said President Clinton wanted Mikulski, who is of Polish descent.
"The president specifically asked her," he said.
Rockefeller, who also ranked below the Senate average of 98.6 percent, missed 16 votes, give him the third-worst percentage in the Senate.
The missed votes included the nominations of Secretary of State Madeline Albright and Defense Secretary William Cohen; votes on nuclear waste legislation; the National Defense Authorization Act; and legislation to establish education savings accounts.
Rockefeller spokesman Jim Whitney said the senator believes voting is important but added that sometimes other responsibilities take precedence.
For instance, he said Rockefeller missed several votes on April 15 when he was in Pittsburgh trying to settle a steel strike. He missed another vote in June when he was at the White House negotiating last year's balanced budget deal.
Rockefeller also missed votes in January when he was in Japan seeking to lure firms in West Virginia; on July 25 when he hosted a manufacturing summit in West Virginia; and on July 22 when he was the featured speaker for the Southern Legislatures Conference in Charleston, W.Va.
Whitney said Rockefeller also missed votes for personal reasons. The death of his aunt took the senator out of town in May and he missed two votes on Oct. 31 due to knee surgery.
"He was either working to bring jobs to the state or he had a family emergency," Whitney said. "He doesn't want to miss any votes.
Rep. Bud Shuster, R-Pa., whose voting attendance was slightly above the House average, missed mostly procedural votes, according to Tim Hugo, his chief of staff.
"He has a responsibility to show up and vote and do the right thing. He tries to do that," Hugo said.
Voting attendance has averaged above 95 percent in the House and about 97 percent in the Senate during the 1990s, according to Roll Call. The percentage has been rising steadily for most of the last 20 years. Congress as a whole was below 90 percent in 1980.
"Everyone was above 90 percent. That used to be considered good," said Fiesta, Mikulski's press secretary. "Patterns have changed."