The amount of money they had given already was historic for Pennsylvania - and now, it's more.

Joel Greenberg, Arthur Dantchik, and Jeff Yass - all executives at the Susquehanna International Group L.L.P. of Bala Cynwyd - started over the winter by indirectly giving $1.5 million to State Sen. Anthony Hardy Williams' Democratic campaign for governor.

The cash allowed Williams, who belatedly entered the race in February, to pour out a Niagara of TV ads leading up to Tuesday's primary.

The three businessmen, who are involved in international finance, did not stop there.

A political-action committee largely bankrolled by the trio gave an additional $975,000 last month to the Williams campaign. The PAC also paid a $200,000 TV bill for Williams.

Now comes word that the same PAC - called Students First - has chipped in an additional $515,000.

On May 3, according to campaign-finance reports filed with the Pennsylvania Department of State, Williams was down to his last $127,000.

Three days later, last Thursday, Students First contributed $515,000.

Joe Watkins, director of the PAC, based in Wynnewood, said he did not know exactly how much of the PAC's funds came from Greenberg, Dantchik, and Yass.

But he said they had remained "very generous" to the PAC, which promotes "school choice," including the use of public vouchers to pay for tuition at nonpublic schools.

Mark Nevins, a Williams campaign spokesman, said Wednesday that he also did not know what portion of the latest donations came from the Susquehanna Group executives.

Combined with their $1.5 million at the start, the total could be in the neighborhood of $3 million or more.

Barry Kauffman, director of Common Cause Pennsylvania, was running out of descriptive words Wednesday night to describe his amazement at the sums of cash Williams has received from individuals.

Kauffman had said the earlier donations put the 2010 campaign for governor into "a whole new level of the ionosphere."

Last night, he trotted out the word stratosphere.

"It creates some serious concerns as to whether a tiny, tiny handful of donors giving massive amounts of money can launch a candidate from nowhere. . . . Is this healthy for our system or not?"

Besides the three Bala Cynwyd executives, Williams has received two other donations that overshadow anything taken in by other candidates for governor.

Barre Seid, a Chicago businessman, gave him $700,000. Henry Rowan, after whom Rowan University is named, gave $600,000.

Pennsylvania is one of 11 states that have no limits on the size of campaign donations from PACs and individuals.

Allegheny County Executive Dan Onorato, who still holds a substantial lead in the Democratic primary polls and who overall has raised more money than Williams, has received several gifts of $100,000 each for his campaign.

Republican front-runner Tom Corbett, the state attorney general, has received a $180,000 contribution.

Tim Potts, founder of the political-reform group Democracy Rising PA, said it was better for candidates to depend on "a broad base of support."

"That has become more and more important in a media age when people get most of their information from what they see on TV and the Internet," he said.

None of the Susquehanna Group executives could be reached for comment Wednesday.

Watkins, who has acted as their spokesman, said the trio wanted nothing from Williams - or from state government - except to push "school choice" onto the political agenda.

"It's a good thing when people care deeply about an issue," he said. "The whole idea is to put students first. . . . I think it is noble."

All of the four Democrats and two Republicans running for governor are still taking in donations.

Asked if Williams' big donors might donate yet again, he said: "You'll see more."