While polls show President Barack Obama beginning to widen his lead over Republican rival Mitt Romney nationally and in key states, first lady Michelle Obama had a message for supporters Friday at Morgan State University: Take nothing for granted.

"As my husband has said, this election will be even closer than the last one. That is a guarantee," she told a raucous crowd of 2,000 at the Murphy Fine Arts Center. "It may all come down to what happens in just a few battleground states."

She urged the audience to talk to classmates, friends, relatives, parents; to make sure everyone is registered to vote; and, for those who are able, to consider traveling to Virginia, where the race remains closely contested, to work for the Obama campaign.

"With just a few evenings on a phone bank, you know, just a few hours knocking on some doors, you could swing an entire precinct for Barack Obama all by yourself," she said, as the crowd cheered.

With less than seven weeks to the Nov. 6 election, the most popular member of the Obama campaign came to Maryland on Friday to raise money and to fire up supporters.

The first lady's visit Friday included the appearance at Morgan State and a reception later at the Residence & Art Galleries of Robert E. Meyerhoff in Baltimore County.

Her comments at both places reflected themes she touched on during her speech this month at the Democratic National Convention and in campaign appearances since then.

The first lady is being deployed by the campaign as chief character witness for the president, steering clear of attacks on Romney in favor of sharing personal details — her husband's decision to turn down high-paying jobs at the start of his career so he could focus on "fighting to get folks back to work in struggling communities," to take one example — intended to strike a favorable contrast.

It's a time-honored role that she has performed before friendly audiences in Virginia, Florida and North Carolina over the past week, offering relief from the more common exchange of charge and countercharge between the candidates and their running mates, as in the back-and-forth Friday between Obama and Republican vice presidential nominee Paul Ryan over Medicare and Social Security.

Speaking by video feed to an AARP convention in New Orleans, Obama called Ryan's plan to turn Medicare into a voucher program "a bad idea." Ryan, addressing the group in person, said Medicare needs to be reformed if it is to be preserved for future generations.

At Morgan State, Michelle Obama walked onstage to roars from the crowd. Much of the state's Democratic leadership was on hand; she acknowledged Gov. Martin O'Malley, Baltimore Mayor Stephanie Rawlings-Blake, Sens. Ben Cardin and Barbara A. Mikulski and Reps. Elijah Cummings, Donna Edwards and John Sarbanes.

During a half-hour address, she spoke of why she fell in love with her husband — his character, she said — and listed what she said were the accomplishments of his first term.

She named the recovery of the auto industry and the addition of millions of private-sector jobs; the health care overhaul that allows students to stay on their parents' insurance until they are 26; the death of Osama bin Laden; and the end of the war in Iraq.

"We cannot turn back now. We have come so far. But we have so much more to do."

She spoke of how close the 2008 election was in the states of Virginia and North Carolina — longtime Republican strongholds that Obama won — and urged supporters to approach campaign workers after her speech.

Tickets to the event started at $250, the campaign said; students were allowed in for $25.

More than 115 supporters attended the reception hosted by Rheda Becker and Robert E. Meyerhoff later Friday at the Meyerhoff estate in Phoenix. Tickets to that event, which was to feature musical performances by Yo-Yo Ma, Leon Fleisher, Pamela Frank, Hilary Hahn and Jaime Laredo, started at $5,000.

Proceeds from the fundraisers were to benefit the Obama Victory Fund, a joint fundraising committee of Obama for America, the Democratic National Committee and several state Democratic parties.