Unleashed by the April US Supreme Court decision striking down a cap on individual donations to federal candidates, 29 heavyweight Massachusetts donors have blown past previous limits during this election cycle, federal records show.

Big-pocketed Massachusetts donors favored Democrats over Republicans by a more than 3 to 1 ratio – with the top donors giving a total of $5.7 million, according to data provided to the New England Center for Investigative Reporting by the Washington, DC-based research group, Center for Responsive Politics. This funding exceeded the previous $123,200 aggregate caps per individual by $2.1 million, data shows.

Nationwide, 495 individuals have exceeded the old federal limits that were stuck down by a 5-4 U.S. Supreme Court ruling.

Critics – who have worried that the top court decision would give wealthier Americans even greater influence in the political process – say the new numbers reinforce their fears. Sarah Bryner, the center’s research director, says she is surprised to see such a large number of donors exceeding past caps even before the end of the current election cycle. The center recorded donations given between Jan. 1, 2013 through Oct. 15, although researchers say numbers could be even bigger because some donations may still not yet be recorded electronically.

“The main takeaway we have is that wealthy single donors are able to exert even more influence on members of Congress and political parties,’’ says Bryner.

Dan Backer, the attorney who represented Alabama businessman Shaun McCutcheon before the Supreme Court, however, sees great news in the burst of giving – showing that more people are involved in the political process. The Supreme Court majority ruled that restricting the number of donations a person can make does not prevent corruption, but limits the democratic process under the First Amendment.  “I think it is an incredibly stupid argument that money buys influence,” Backer says.

The top court ruling, known as McCutcheon vs. Federal Election Commission, eliminated the $123,200 cap on the total amount of money any individual can give to federal candidates, party committees and some types of political action committees over a two-year period. Under new rules, donors still are limited on how much money they can give to each individual candidate and political group. For example, donors may contribute up to $2,600 per election to a federal candidate and up to $32,400 per calendar year to a national party committee.

Topping the big-donor list in the Bay State, retired businessman Tatnall Hillman of Chilmark, Mass. gave  $403,659 since the beginning of 2013 – $265,759 of which was earmarked for Republican causes, data shows. The funding exceeded the previous aggregate cap by $280,459, according to the Center for Responsive Politics. Hillman, who ranked No. 2 nationally among those who exceeded previous caps, declined to comment for this story.

Businessman Arnold S. Hiatt, former president of the Lexington-based Stride Rite footwear,  was second on the list of Massachusetts donors and 12th nationally. He gave $290,500 since 2013 -- $248,400 funneled to Democratic committees and candidates, according to data. Hiatt’s donations exceeded the past cap by $167,300. Hiatt could not immediately be reached for comment.