Source: National Institute on Money in State Politics

Minnesota failed a national campaign spending transparency test for the second year in a row.

The National Institute on Money in State Politics failed Minnesota because the state does not require independent political spenders to disclose all information about so-called electioneering communication. Electioneering communication tends to be messages to voters that addresses campaigns but is not specifically backed by candidates and does not tell the populace to vote for or against specific candidates.

In Minnesota, many political action committees and other interest groups must reveal fundraising details but political non-profits can largely avoid releasing details of their spending. To voters, the messages from the two types of organization may look nearly identical.

Minnesota had significant company at the bottom. The state joins 23 other states in getting an 'F' rating in making independent political spenders disclose information, according to institute.

The state also failed the institute's 2013 disclosure test. Since last year, other states improved their rankings.

In 2014, Gov. Mark Dayton and many lawmakers pushed to increase campaign spending disclosure. That effort failed to muster enough votes to become law.