An ad depicts Mark Udall the Democratic Senator from Colorado as a clone of President Obama who twists the truth. Another portrays Thom Tillis a GOP Senate candidate as a destroyer of families and a tool for special interests.

The attacks on television in ad campaigns reveal interesting themes taking place in the election races for 2014: a midterm election that has been one of the most negative with an unprecedented amount of unknown funding from secret donors.

While negative ads are not new, voters in 2014 have been inundated with them. Close to 75% of the ads for races in the U.S. Senate during a 14-day period during August and September showed candidates in a negative light.

The increase in donations that are undisclosed stems from the decision by the Supreme Court in 2010, which enables outside groups to donate unlimited sums of money as long as they are not coordinating efforts with one of the candidates. This is the first midterm election where this practice has been in full force.

The impact can be since on television and online. One out of every 16 ads on television in races for the U.S. Senate between January 2013 and August 2014 were paid by one group, American for Prosperity.

AFP is a nonprofit advocacy arm for a political network that is backed by David and Charles Koch two billionaire and conservative brothers.

Election money comes from many different sources including the national organization of a party, PACs political action committees that are run by organizations such as business and labor, campaigns themselves and individual contributors.

The decision by the Supreme Court paved the way for the Super PACs that have no restrictions on what they spend but must disclose donors.

It has also helped fuel growth of the political nonprofits, sometimes called dark money that are not required to disclose donors.

The secret donor groups this year have attracted huge contributors and criticism that just a few wealthy Americans hold big influence on U.S. politics.