A billionaire investor who spent more than $25 million to defeat President Bush in 2004, George Soros, is giving a financial boost to the political fortunes of a former four-star general, Wesley Clark, who ran for the Democratic presidential nomination in 2004 and is poised to mount another bid in 2008.

Mr. Soros gave $75,000 in July to a political group led by General Clark, Wes-Pac, according to a report filed yesterday with the Internal Revenue Service.

It is the largest known gift from Mr. Soros this year to a political organization affiliated with a contender for the presidency in 2008.

Spokesmen for the two men did not return calls last night seeking comment on the donation.

In April, Mr. Soros hosted a fund-raiser for WesPac at his home in Manhattan. General Clark also serves on the board of a nongovernmental organization supported by Mr. Soros, the International Crisis Group.

Last year, Mr. Soros gave the legal maximum of $4,200 to Senator Clinton’s re-election campaign. According to a report filed Federal Election Commission, some of the money, $1,250, was later refunded. No reason was given.

Due to legal limits on donations to political groups affiliated with current federal officeholders Mr. Soros could not have given $75,000 to Mrs. Clinton even if he wished to. However, the financier could give $5,000 a year to Mrs. Clinton’s political action committee. He has not done so.

In an interview last week, Mr. Soros said he could support Mrs. Clinton in a bid for the White House. “I would be delighted to see her as president,” he told Fox News. He did not offer an opinion on other possible contenders for 2008.

Nearly all the major contenders for the presidency in 2008 have started political action committees to finance their travels to key states and provide a vehicle for relaying donations to local candidates. Several, such as General Clark, have also formed so-called 527 groups, which can take gifts of unlimited size but cannot support individual candidates.

Current federal officeholders and candidates are not permitted to be affiliated with 527 organizations, which get the label from a section of the tax code.

The largest gift to General Clark’s political committee was a $100,000 contribution from the owner of a Texas sporting goods chain, Arthur Gochman.

General Clark, a Rhodes scholar, began his military career as an Army Ranger in Vietnam, where he was wounded four times. He retired after commanding NATO forces in Kosovo as supreme allied commander-Europe.