The Washington Post poll showed Erlich and Townsend each claimed 47 percent of likely voters, while six percent were undecided. The margin of sampling error is plus or minus 3 percentage points.
The poll also found that Erlich held a small advantage among the most committed voters who say they will cast a ballot Nov. 5, which means turnout will be crucial.
The Post survey suggests that turnout among black voters, in particular, could be crucial to Townsend's hopes of capturing the governor's mansion.
If black voters turn out in numbers similar to 1998, when they accounted for 21 percent of the electorate, Townsend could win, the Post reported. But if blacks stay home, then Erlich is poised for victory, the poll found.
White voters, however, heavily favored Erlich, 58 percent of 38 percent, the poll said.
Meanwhile, the choice of a running mate had little impact on voters' decision about which candidate to support, the poll found.
If Ehrlich, 44, wins on Nov. 5, he would be the first Republican governor of Maryland in more than 30 years. Townsend, 51, the state's first female lieutenant governor, would be the first woman to ascend to its governor's office.