Massachusetts voters sent Scott Brown to the US Senate, but the flood of cash coming into his campaign from around the country indicates his race against Attorney General Martha Coakley was in many respects a national referendum.

Nearly 76 percent of the big-donor money Brown raised in the final three weeks of the campaign came from out-of-state contributors. The comparable figure for Coakley was 63 percent. Both percentages were well above what is normal for a US Senate race.

While final campaign finance reports aren’t due until next month, Eric Fehrnstrom, Brown’s campaign manager, said the Wrentham lawmaker received about two-thirds of all his contributions from outside Massachusetts.

“People around the country began to notice and realize he could be the 41st vote against a bad health care bill,” said Fehrnstrom. “That’s when the money really started coming. … Beginning around the 1st [of January], all we had to do was hit the refresh button on the computer.”

From New Year’s Eve to the election, Brown received more than 1,700 donations of $1,000 or more from 48 of the 50 states. More than 1,000 donations of greater than $1,000 went to Coakley from 44 of the 50 states. Only Idaho and North Dakota went unrepresented on both lists.

Massachusetts contributors led the way in total dollars for both Brown and Coakley, but donors from California and Texas were in a virtual tie for second for Brown, accounting for $257,000 and $256,000, respectively, in donations of $1,000 or more. New York and Florida were the only other states to contribute more than $100,000 to Brown, with New Yorkers sending nearly $180,000 while those in the Sunshine State coughed up nearly $160,000.

Coakley appeared to be the choice of Washington, D.C., workers and residents, who sent in more than $309,000 — 17 percent of her large donor totals — compared to just $32,000 for Brown from inside the Beltway. Coakley received more than $100,000 from two other states — California, at $169,000, and New York, at $131,000.

Political action committees and campaigns directly donated a stunning $417,900 to Coakley, while similar groups gave $112,400 to Brown in the last three weeks of the campaign.

Retirees swamped Brown with $364,500 in last-minute contributions, far more than the $112,100 Coakley received.

Mark Feighner, a retired executive with GTE Corporation and former venture capitalist, said he followed the race closely, including watching the debates on the Internet and C-SPAN. While health care was a dominant issue for him, he says he found Brown’s positions on a number of issues to be more “independent” and, in most cases, in line with his own conservative views. He said he had nothing against the late Sen. Edward M. Kennedy but was surprised that a Republican was within striking distance of winning the seat.

“I saw somewhere that [Brown] was only 10 or 15 points behind Coakley and I thought, ‘Wow, for Ted Kennedy’s seat, for somebody to be that close, I’m going to give some money and we might make a difference,’” he said.

Those who identified themselves as a medical practitioner or working in a medical or health care-related field donated $82,000 over the last three weeks to Brown and $60,000 to Coakley. Coakley was the beneficiary of an additional $13,400 from medical and health care political action committees.

A story in the Boston Globe on Monday stated the Brown received at least $442,000 from members of the financial services industry, while Coakley pulled in $92,000 from that sector in the campaign’s final six days. Those figures could not be verified by CommonWealth.

According to a CommonWealth review of last-minute filings with the Federal Election Commission, Brown’s campaign raised $2.6 million from donors of $1,000 or more, compared with $1.8 million by Coakley from the same group in the final three weeks of the campaign, when the bulk of donations were raised. Brown’s large donors represent about a fifth of his total donations, while Coakley’s last-minute large donations amount to nearly 46 percent of her total.

Brown overall dwarfed Coakley in fundraising by more than a 3-1 margin, with Brown raising an estimated $14 million to about $4 million for his Democratic opponent, according to each camp.

Several calls to Coakley’s shuttered campaign headquarters and campaign aides were not returned.

Edward Gallegos, who owns an oil and gas production company in Stillwater, Oklahoma, said he and his wife each gave the $2,400 maximum donation because they saw Brown as someone who will bring “common sense” to Washington. Gallegos, like others, said he never thought a Republican would have a chance to grab the seat held by Kennedy for nearly a half-century or be elected by the same state that returns John Kerry to the Senate.

“[Brown] seemed to be a very down to earth, realistic guy, the kind of guy you’d go have a beer with,” Gallegos said “The primary motivation was that he would be the 41st vote against health care. As other issues come down the pike, like cap and trade, hopefully he’ll be the 41st vote on those.”

John Reed, a rancher from Omaha, Nebraska, who ponied up $1,000 for Brown’s campaign, said he “absolutely” supports health care reform, just not the plan currently in play. He said he read up on Brown on the Internet and in news accounts and liked what he saw as the candidate’s independence.

“I agree with his principles that he was espousing, and I was very pleased as an American to be able to contribute,” Reed said. “Even if [Brown] didn’t win I wanted to participate and help the best I could. I don’t believe our Congress or president is focused on issues that count in the economy.”

The out-of-state impact is far above the recent national average, according to one study. Last August, the Center for Responsive Politics analyzed the first six months of 2009 fundraising and found that the average US senator raised 57 percent of his or her money from outside of their state, while the average member of the House pulled in just 23 percent from beyond their state borders.

While some people who sent Brown checks from around the country cited his oft-repeated stance to be the key vote to halt the congressional health plan as one reason they took notice of the little-known state senator, they insisted it is the broader potential impact a conservative vote in the Senate could have on changing the direction of Congress.

Brown had the distinct advantage among athletes, with former Red Sox pitcher Curt Schilling, former Patriots quarterback Drew Bledsoe, and race car driver John Popper all donating the maximum $2,400, while Coakley received the financial support of team executives with Sox owner Tom Werner, team president Larry Lucchino, and Celtics co-owner Stephen Pagliuca, who lost the Democratic primary to Coakley. The attorney general also came up big among the Hollywood types, with Barbara Streisand, Sam Waterston, and Sharon Stone making $1,000 donations each, while Brown got some of Ben Stein’s money and a $1,000 contribution from actor Gary Sinise.

Both campaigns were also bolstered by millions from outside groups, with the US Chamber of Commerce leading the charge for Brown and Coakley being the beneficiary of the labor group SEIU. According to FEC electioneering and late expenditure filings, which are required for large advertising outlays in the last 30 days of a campaign, a total of $8.6 million was spent on advertising in the race, about half of that from outside groups.

In the last two weeks of the campaign, outside groups spent more than $200,000 on email blasts, Internet newsletters, and Web ads — an astonishing amount given the fraction of the costs for advertising on the Internet versus regular media. The amounts for Brown ranged from $95.26 from the National Organization for Marriage, which opposes same-sex marriage, for email blasts on the day before and election day, to more than $132,000 on Internet-related spending by the Our Country Deserves Better PAC, the political action committee of the Tea Party Express.

Although Fehrnstrom insisted the “Tea Party stuff is a little bit overblown,” the Our Country deserves Better PAC spent more than $420,000 on ads, automated calls, emails, and Internet newsletters in support of Brown between Christmas and the special election.

“His general conservative views on smaller government and just the country going to hell,” was why she gave $2,400 to Brown, said Carol Oswald, who identified herself as a homemaker from Prosper, Texas, and a self-described Tea Party member.

CommonWealth staffers Bruce Mohl, Gabrielle Gurley, Alison Lobron, David Sloand and Alison Singer contributed to this report.