The race is tied with Burke and Walker each getting 46 percent support among registered voters while 6 percent are undecided, the poll found.
That's a much closer race than what a previous Marquette University poll found. That last poll, in March, found Walker leading Burke 48 percent to 41 percent, among registered voters.
The picture is somewhat better among likely voters, the new poll found. Forty-eight percent said they support Walker while 45 percent said they would support Burke.
Burke's campaign quickly highlighted the poll in multiple emails to supporters.
"The new direction and clear plan for growing Wisconsin's economy, creating more good paying jobs and strengthening the middle class offered by former Trek Executive MaryBurke stands in stark contrast to Scott Walker's failures," Burke communications director Joe Zepecki said in a statement.
The poll's margin of error was plus or minus 3.5 percentage points. The survey was conducted from May 15 to 18 among 805 Wisconsin registered voters.