Democrats and many in the media routinely complain about money spent in politics, and they regularly lash out at conservatives and big business. Turns out, unions are the top spenders in politics.

Twelve of the top 20 political donors from 1989 to 2014 have been unions, which overwhelmingly support Democratic causes, according to an analysis done by OpenSecrets.org's Center for Responsive Politics.

Seven of the top 10 donors overall give almost exclusively to politicians or groups on the left.

ActBlue, a political action committee that raises money for Democrats and progressive causes and features Michigan Democratic gubernatorial candidate Mark Schauer on its "Hot List" of state and local of candidates on its website, topped the OpenSecrets list with $97.4 million spent within that time frame. Ninety-nine percent of it supported Democrats.

The American Federation of State, County and Municipal Employees was No. 2. The union, which represents Detroit workers and other across the state, spent $60.9 million, with 81 percent going to Democrats; 1 percent went to the GOP.

The parent union for the Michigan Education Association, the National Education Association, came in at No. 3 and spent $58.5 million, with 56 percent going to Democrats. The NEA gave 4 percent to GOP candidates, according to OpenSecrets, a nonpartisan organization that tracks money in politics.

The other unions making the Top 10 for donations from 1989-2014 were:

• No. 6: International Brotherhood of Electrical Workers, $45.1 million
• No. 8: United Auto Workers, $41.7 million
• No. 9: Carpenters & Joiners Union, $39.8 million
• No. 10: Service Employees International Union, $38.4 million

All of those labor unions gave overwhelmingly to Democrats, according to OpenSecrets.org.

AT&T Inc. landed at No. 4 for political donations. The telecom company gave $56.7 million between 1989-2014 with 41 percent going to Democrats and 57 percent to Republicans. The National Association of Realtors was No. 5, spending $51.4 million with 44 percent to Democrats and 47 percent to Republicans. Goldman Sachs came in at No. 7, having spent $44.9 million on politics. It gave 53 percent of its money to Democrats and 44 percent to Republicans.

Antony Davies, an associate professor of economics at Duquesne University, said the disturbing thing isn't the amount these special interests spent, but "the asymmetry" in their contributions.

"Corporations tend to spend equally on Republicans and Democrats. So the effect corporations have on legislation is 'around the edges' rather than across the board," Davies said. "Unions, however, are not only the largest contributors but they give almost 90 percent to Democrats. I am not concerned that they give to Democrats versus Republicans, but that they would make any single party so beholden to them is disturbing."

The National Education Association has made a point to say that it represents teachers who are considered to be conservative politically. In the Michigan Education Association's October 2010 magazine, it was reported that NEA statistics showed 45 percent of teachers under 30 classified themselves as conservative and 63 percent of teachers aged 40 to 49 considered themselves conservatives. Yet, OpenSecrets.org reported the NEA gave only 4 percent of its money to GOP campaigns.

The American Federation of Teachers, which represents Detroit teachers, was No. 12 on the list and spent $36.7 million. It gave 89 percent of its money to Democrats and didn't give any to the GOP.

"The list shows that the true money in politics comes from Big Labor," said F. Vincent Vernuccio, director of labor policy at the Mackinac Center for Public Policy. "The unfortunate part is that while union political money may support the interest of union leaders it does not reflect the ideals of many union members. Generally, well over 90 percent of labor's political giving and endorsements go to Democrats, but 40 percent of union members typically vote Republican."

(Correction: This story has been edited since its original posting. Some of the numbers have been updated.)