After a slow start, the U.S. Senate race in Maryland has suddenly come to life.

In the past week, Sen. Barbara A. Mikulski (D), the three-term incumbent, and her opponent, state Sen. Edward J. Pipkin (R), have turned up the volume with a series of radio and television ads in the Washington and Baltimore areas.

Pipkin (R-Queen Anne's), in his first term in Annapolis, had been keeping a relatively low profile. But at least one recent poll showing President Bush running better than expected in Maryland spurred him to begin a new push, an aide said.

The 48-year-old former bond trader has put more than $600,000 of his own money into the race and is expected to contribute more to a campaign treasury that has at least $1.2 million; Mikulski has about $5.5 million.

Pipkin's spending will allow Mikulski to raise more money. He has triggered the "millionaire amendment," a provision of the McCain-Feingold campaign finance law that allows opponents of self-financed candidates to increase their own contribution limits. Individual contributors to Mikulski, ordinarily limited to $2,000 per election cycle, will now be able to contribute up to $6,000.

In the past week, Pipkin has aired two new television ads and a radio spot criticizing Mikulski on votes for tax increases and against military spending. Mikulski, 68, the Senate's most tenured woman and a member of the Appropriations Committee, is airing more personal spots depicting her south Baltimore roots and commitment to public service, inspired by her father's work behind the counter in the family grocery store.

Polls have shown Mikulski running well ahead of Pipkin even as Bush has made gains in Maryland, which is about 2 to 1 Democratic.

In his latest ads, Pipkin charges that Mikulski has voted for higher taxes 350 times in her Senate career, opposed new equipment for U.S. troops and voted against funding for the B-2 bomber and the F-18 fighter.

"She gives the impression of caring about Maryland interests first, but her voting record shows otherwise," said Aileen Kelly, a Pipkin spokeswoman.

Mike Morrill, Mikulski's campaign manager, said Pipkin was using a game plan devised by national Republican strategists.

"His ads are not consistent with her record," Morrill said. He said the Pipkin campaign was often looking at votes that did not carry real weight or were on combined bills that had other items Mikulski opposed. For example, one of Pipkin's ads said Mikulski voted consistently against military pay increases during her tenure. Morrill said Mikulski had voted 17 times for military pay increases since coming to the Senate.

Mikulski said Saturday at a "progressive summit" for Maryland Democrats that she did not want to "hear a peep out of Pipkin." But that remark was followed by comments suggesting the senator does not view her challenger quite so dismissively.

"They're after me the way they were after Kathleen," she told an enthusiastic crowd of several hundred, referring to the Republicans' 2002 defeat of gubernatorial nominee Kathleen Kennedy Townsend.

Campaigning at a Bethesda food festival later that day, Mikulski told reporters that she did not think Pipkin was gaining on her. "But I'm not taking anything for granted," she said. "You hit me and I'll know how to fight back."

Staff writer Cameron W. Barr contributed to this report.

In his new ads, state Sen. Edward J. Pipkin (R) charges that U.S. Sen. Barbara A. Mikulski (D) has voted for higher taxes 350 times in her Senate career. Polls give Mikulski a comfortable lead in her bid for reelection, but "I'm not taking anything for granted," she said.