The primary winner will face either ex-gubernatorial aide Bill Hoppner, the presumed Democratic front-runner who lost the 1990 primary to Nelson by 42 votes, or former state Sen.

CNN: Republican Prospects Strong in Nebraska

W. Bush, in his bid for the Republican nomination that year, went into the May 20 primary badly trailing front-runner Ronald Reagan.

NPR: Political Junkie: Obama's Former Pastor Speaks Out

Ms. Quinn's decision to sign onto the legislation comes amid escalating pressure on the front-runner in the Democratic mayoral primary.

WSJ: Quinn Signs On to Paid Sick Leave