By Alina Selyukh
WASHINGTON (Reuters) - The Super PAC backing Republican presidential candidate Mitt Romney said Tuesday it would launch a $7.6 million television ad sweep across nine states, its latest contribution to the growing media presence of outside spending groups in the U.S. election.
The purchase comes after weeks of silence from Restore Our Future, the independent spending group that emerged as the deep-pocketed heavyweight that barraged Romney's Republican competitors in the race to become their party's nominee.
The ads will begin airing Wednesday and run through the end of June in presidential battleground states of Colorado, Florida, Iowa, Nevada, New Hampshire, North Carolina, Ohio, Pennsylvania and Virginia, according to PAC spokeswoman Brittany Gross.
The Super PAC backing President Barack Obama's re-election, Priorities USA, has been on air in five of those states since late May with $7 million worth of ads that hit Romney over his tenure at a private equity firm.
Outside groups are raking in unlimited funds to spend on advertising, largely negative. Spawned by a 2010 U.S. Supreme Court decision, Super PACs have no limits on how much they can raise or spend on political candidates, as long as they do not coordinate with official campaigns.
In three of the battleground states - Colorado, Florida and Nevada - Priorities USA has also partnered up with the Service Employees International Union for a $4 million Spanish-language ad buy this week criticizing Romney's immigration stance.
More than $1 billion is expected to be spent on both sides of the aisle in the run-up to the November presidential election.
(Editing by Doina Chiacu)