MADISON, Wis. (AP) -- Longtime Madison Mayor Paul Soglin is launching his campaign for governor attacking both President Donald Trump and Gov. Scott Walker.

Soglin officially joined the race Wednesday after months of speculation. Soglin is in his 20th year as mayor of Madison, a position he's held off and on since 1973.

Soglin becomes the ninth top-tier Democrat in a crowded field that will square off in the August primary. The winner will take on Walker as he seeks a third term in November.

The 72-year-old Soglin hopes to tap into supporters of liberal former presidential candidate Bernie Sanders who won the Wisconsin primary in 2016. Soglin says that both Trump and Walker do not believe in the principles of "equal justice under the law."