Maryland Democratic gubernatorial candidate Anthony Brown, left, and Republican candidate Larry Hogan debate at Maryland Public Television's studios this month. (Patrick Semansky/AP)

The Cook Political Report, one of the nation’s leading prognosticators, on Friday declared Maryland’s gubernatorial race to be a “tossup,” giving rise to more speculation that Republican Larry Hogan could pull off a major upset in the heavily Democratic state.

The publication, which had previously labled the race “leans Democrat,” said it still believes that Lt. Gov. Anthony G. Brown (D) “enjoys a slight advantage.”

But, Cook said, “polling and the barrage of television ads from both sides suggest that this belongs in Toss Up.”

A Washington Post-University of Maryland poll this month gave Brown a 9 percentage point advantage over Hogan, an Anne Arundel County businessman. Most public polling has shown Brown with a lead in the single digits.

Jennifer Duffy, senior editor on the Cook staff, said the change in the race’s rating was based in part on other polls she has seen.

“I’m aware of polling that has this race well within the margin of error, and it has been for several weeks,” she said.

Hogan has run a campaign narrowly focused on economic issues, making tax cuts a rallying cry in a state where the popularity of Gov. Martin O’Malley (D) has dropped in recent months.

Cook said that “both parties acknowledge that this contest ... has gotten very close.”