The key battlegrounds in this election could be Montgomery and Prince George's counties, which are overwhelmingly Democratic but had low voter turnout in September's primary.
Both tickets are rallying support among local voters.
Political coverage from NBC4.
The team of Ehrlich and Mary Kane attended a Moms for Ehrlich coffee at Krispy Kreme in Rockville, greeting supporters and saying there is one strategy for success at this point.
"We've identified the folks that are most enthusiastic about our campaign," Ehrlich said. "Getting them to the polls, getting them to vote, is absolutely essential right now."
Kane, who is running for lieutenant governor, lives in Montgomery County and knows that a good showing there is very important for victory.
"There's a high concentration of independents and a lot of Republican votes here in Montgomery County," she said. "Do we have to win 50 percent? No, we don't, but we'd like to be up in the high 30s like we have been in the past."
Their supporters are hard at work.
"We've been phoning likely Republicans, independents and women, and we've been doing about 5,400 to 5,600 calls a day," Janet Gosnell said.
While O'Malley concentrated his efforts on Baltimore, his running mate, Lt. Gov. Anthony Brown visited Prince George's Community College to speak with students, saying the Democratic ticket needs a good turnout here.
"In the September primary, it wasn't what we really wanted to see, but as I see in Prince George's County, whether at the Metros or the shopping centers or going door-to-door knocking in the community, there's a lot of enthusiasm, there's a lot of excitement," he said. "I'm expecting a big turnout for O'Malley-Brown because Prince Georgians recognize that under Gov. O'Malley's leadership we've been making a lot of progress."
Will students there help get out the vote? Political science professor Melinda Frederick thinks so.
"I think it will help them understand how voting really is about empowerment and will bolster motivation and participation," she said.
Student Janice Garcia was convinced.
"I'll be voting for them because I do believe they care about the PG educational system," she said.
O'Malley's counting on a good showing in the Washington suburbs and the City of Baltimore.
Ehrlich is showing strong support in Baltimore County, the Eastern shore and western Maryland.
Both sides say turnout is the key to victory.