Investors have pushed more than 120 public companies in the U.S.to reveal previously confidential details of their politicalspending even as regulators remain deadlocked over whether tomandate such disclosures.

Thirty-one companies — up from 28 last year — will holdshareholder votes in 2013 on resolutions calling for disclosure ofhow much they spend to influence politics, according to theWashington-based Center for Political Accountability, which helpswrite the resolutions. The first of those votes, at Humana Inc.'sannual meeting, is scheduled for today.

Another 16 companies, including Boeing Co., KeyCorp, QualcommInc., and Southwest Airlines Co., have agreed to provide investorswith data on their political spending this year in an effort toavoid shareholder votes mandating the disclosures.