Senate Majority Leader Bill Frist (R-Tenn.) and his top financial supporters continued to churn out donations at a rapid clip last quarter, doling out more than $660,000 to campaign accounts and party committees.

New disclosure reports show that Frist’s Volunteer PAC, his leadership political action committee, had its busiest quarter yet pumping money into the political economy — part of a multimillion-dollar operation with a primary goal of keeping the Senate in Frist’s control next year.

Frist handed out more than $220,000 in direct PAC contributions to Republican candidates, mostly in tight House races, and he steered $440,000 in bundled donations of his supporters into the campaign coffers of key Senate races.

The top recipients of Frist’s largess from April through June were challengers or Senate candidates in open-seat races. Three received at least $90,000 in bundled contributions from Frist donors: Sen. Lisa Murkowski (R-Alaska) and Reps. David Vitter (La.) and George Nethercutt (Wash.).

Frist’s political machine has been driven by bundling contributions from his donors, then sending that money from Volunteer PAC to the campaigns themselves. This allows Frist to take credit for giving far in excess of the $10,000 that VolPAC is limited in giving to campaigns for the primary and general elections during each cycle.

According to reports filed with the Federal Election Commission, Frist has bundled at least $1.2 million from his donors to Senate candidates in the first 18 months of this election cycle. Nine campaigns have received between $90,000 and $200,000 from Frist’s top contributors in earmarked donations.

While President Bush and his top political operatives reaped much of the credit for the GOP’s midterm victories in 2002, they are almost singularly focused on his re-election campaign this fall. In the Senate, few races overlap with key battleground states in the presidential campaign.

That has raised the stakes — and left an opening — for Frist. He could take credit for retaining or expanding the narrow majority, or shoulder the blame for failure.

The top beneficiaries from the leader’s political operation are a handful of incumbents and challengers in top-tier races, but no one has received as much attention as former Rep. John Thune (R-S.D.), who is seeking to oust Senate Minority Leader Tom Daschle (D).

Having steered more than $156,000 in bundled cash to Thune in the first quarter, Frist’s donors ponied up another $43,500 for Thune in the second quarter — pushing Frist up to more than $200,000 in donations for Thune’s campaign.

Frist has been widely criticized by Senate Democrats for his unabashed efforts to oust Daschle. Democrats consider Frist’s open opposition to be a break with Senatorial tradition. But Frist has vigorously defended his actions, saying that a 21st-century Majority Leader has the responsibility to be leader in political as well as legislative matters.

“I am the Republican leader of the political entity known as the Republicans of the United States Senate,” he told reporters last month. “A closely divided Senate. One vote makes a difference.”

Frist’s other top priority has been to return Murkowski to the Senate, for which she first must win a primary and then defeat former Gov. Tony Knowles (D) in the general election.

Murkowski, the only GOP incumbent considered politically endangered this cycle, has taken in at least $157,000 in checks from Frist’s donors so far this cycle.

In addition to his bundling operation, Frist’s VolPAC has been the biggest leadership PAC in Congress measured by dollars raised, taking in donations limited to $5,000 per year. Through the first 18 months of the cycle, VolPAC raked in $3.6 million in contributions.

Frist has used that money in more traditional ways for leadership PACs, doling out checks directly to candidates and party committees. He’s now given more than $556,000 in direct contributions — more than any other Senator has through a leadership PAC.

But having already donated the maximum to every Senate campaign that is even remotely facing a tough campaign, Frist began blanketing House campaigns with donations last quarter. All told, 21 House candidates, mostly incumbents, took in $180,000 from VolPAC.

Five months after joining the Republican Party, Rep. Ralph Hall (Texas) — who is not facing a tough re-election bid — took in a $5,000 check from Frist.

Another thing Frist is doing differently than other leadership PACs is to carry an usually large cash-on-hand balance. As of June 30, VolPAC still had almost $1.9 million in its account. Other top leadership PACs won’t be reporting until today, but few expect any other PAC to report having even $1 million on hand.

At the end of the first quarter, VolPAC boasted $1.6 million on hand, almost $1 million more than any other leadership PAC.

With no Senate races left to influence, Frist will likely target another dozen or so House races and then pump hundreds of thousands of dollars into state party committees in the final run-up to the Nov. 2 elections, a GOP strategist said.