Companies, unions and other interest groups poured about $300 million into campaign ads in the 2010 Congressional elections after the Supreme Court’s Citizens United decision opened the sluices to unlimited spending by independent groups. That will look like a trickle compared with the gusher coming in 2012.

Gov. Rick Perry’s supporters have created a group called Make Us Great Again, which plans to spend up to $55 million to help him win the Republican presidential nomination. Unions and other supporters of Democrats, too, are starting to funnel money into independent groups like Priorities USA Action, which has raised $3.2 million for the presidential race and plans to raise much more.

These groups, which are not supposed to coordinate with candidates’ campaigns or the political parties, are called Super PACs, but the label doesn’t much matter. The point is that in the past several years outside groups — using various types of financing vehicles — have accounted for a growing share of the money spent in federal elections.

The first chart shows the steady rise in total spending in federal elections in both presidential and nonpresidential years over the last decade. Over that time, money spent by outside groups jumped to 8 percent of the total from less than 1 percent, while party spending declined as a share.