ARLINGTON, Va. — As Senator Clinton re-fills her campaign coffers, she has begun the battle with Senator Obama for delegates in the three elections that make up next week’s Potomac Primary.

Voters in Virginia, Maryland, and the District of Columbia all head to the polls on Tuesday, and while advisers to Mrs. Clinton say Mr. Obama has an advantage in the mid-Atlantic region, she is focusing heavily on Virginia.

The New York senator held her first post-Super Tuesday campaign rally here yesterday, addressing a high school gymnasium filled largely with students. And after heading cross-country to campaign in Washington State, she plans to stop in Maine on Saturday and return to Virginia for events Saturday night and Sunday.

Her return to the stump comes as her campaign was trying to reassure donors about its financial viability following the disclosure on Wednesday that she had made a $5 million personal loan to the campaign in late January. Top advisers yesterday told contributors that the campaign had raised $7.5 million in the first week of February, with $6.4 million of that total coming after she effectively tied Mr. Obama in the Super Tuesday contests nationwide.

“We’re doing great. We now have money. We’re going to have a huge, huge, February,” the campaign’s chairman, Terence McAuliffe, told donors in a weekly finance call with donors that reporters were allowed to listen in on.

The campaign has been sending fund-raising appeals all week, and Mr. McAuliffe suggested that the news that Mrs. Clinton was forced to invest her own money had spurred uncertain donors to send checks. “They said, ‘Well, I didn’t know you needed money. I thought you had all money you needed and with Hillary putting money in, I’m there for you,'” Mr. McAuliffe said on the call.

He said the campaign picked up 40,000 new donors since the polls closed on Tuesday and projected that February would be its largest fund-raising month. After Mrs. Clinton and Mr. Obama had run neck-and-neck in fund-raising for most of 2007, the Illinois senator pulled far ahead in January. His campaign claimed to raise $32 million, more than the double the $14 million haul for the Clinton camp. Mr. Obama’s campaign said it had pulled in $7.5 million for the first week of February.

Mr. McAuliffe also said the campaign now had enough money to safely pay its entire staff. Top aides had offered this week to forgo salary for February, but he said that was “not an issue.”

The new money was put to quick use yesterday in Arlington, where the campaign volunteered to pay for school buses to wait for the students it had transported from other schools, because Mrs. Clinton arrived more than an hour late.

The campaign has launched television ads in Washington state and in Nebraska, which vote on Saturday, and in Maine, which holds a caucus Sunday. Ads will also be on the air beginning next week in Texas and Ohio, the two delegate-rich states that vote on March 4. In Virginia yesterday, Mrs. Clinton stuck mostly to her stump speech, although she did begin to draw contrasts with the man she acknowledged was the likely Republican nominee, Senator McCain.

“It appears as though Senator McCain will be the Republican nominee,” she said. “And I have the greatest respect for my friend and my colleague, Senator McCain, but I believe that he offers more of the same. More of the same economic policies, more of the same military policies in Iraq.”

Mrs. Clinton largely held her fire on Mr. Obama. She pointed out that their policies on health care and the mortgage crisis differed, but she did not explicitly criticize his proposals.

A campaign spokesman said 2,700 people were in attendance at Washington and Lee High School, but sections of the bleachers were empty, and many of the students were too young to vote. The campaign also struggled to fill in the area around the stage in the middle of the gym. At one point, an aide asked a group of students seated in the bleachers to move to the floor, where they could stand near the stage. “Anybody want to be closer to Hillary?” the aide asked. There were no takers. “Nobody? Really?”

There are 168 pledged delegates up for grabs on Tuesday in a trio of elections alternately dubbed the “Potomac Primary” or the “Chesapeake Primary.” Mr. Obama’s campaign manager, David Plouffe, told reporters yesterday that they hoped to come out of the day with a larger share of delegates, but he raised the expectations for the Clinton campaign in Virginia, saying her advisers considered the state a “must-win.”

While Mrs. Clinton campaigned in Virginia, Mr. Obama was in New Orleans, where he criticized the Bush administration’s response to Hurricane Katrina in 2005 and outlined proposals to help the city rebuild and boost its protection against major storms. Mr. Obama is favored to win Louisiana’s primary on Saturday, where 67 delegates are at stake. President Clinton is scheduled to stump for his wife across the state on Friday.