MILWAUKEE (Reuters) - Wisconsin Republican Governor Scott Walker widened his lead over Democrat Tom Barrett to 7 percentage points in a new poll released on Wednesday, less than a week before a recall election prompted by Walker's drive to curb labor union power.

Walker had the support of 52 percent of those polled by Marquette University Law School, while 45 percent supported Milwaukee Mayor Barrett. The gap is up from 6 points in the same poll two weeks ago.

The survey of 600 likely Wisconsin voters was taken May 23 to 26 and has a margin of error of 4 percentage points.

The recall election on June 5 was scheduled after Democrats and labor unions collected nearly a million signatures calling for Walker's ouster. They objected to a law he championed forcing public sector union members in the state to contribute more toward health insurance and pensions, put limits on pay increases and forced unions to seek annual recertification.

(This story is filed to correct day of week in first paragraph)

(Reporting by Brendan O'Brien; Writing by Greg McCune)