Rep. Paul Ryan has become one of the top fundraisers in Congress in recent years, drawing on a growing national profile to amass more than $8 million for this year’s election through his campaign and political committee.

A sizable chunk of what the Wisconsin Republican has brought in for his campaign over the years remains in the account — $5 million — giving him more cash on hand than any other House member.

Executives and employees of major financial and insurance companies are Ryan’s biggest and most reliable sources of money. But his recent prominence as the author of a conservative budget plan has attracted the attention of some of the nation’s wealthy conservative donors, including Paul Singer, a hedge fund founder who has donated millions to the Republican Party. Singer and employees of his Elliott Management Co. have given Ryan’s campaign more than $70,000 since 2010.

Ryan has raised nearly twice as much during the 2012 election cycle as he did during the last campaign. And much of that is from thousands of small donors nationwide, aided by millions of dollars he has spent on direct-mail appeals. Corporate PACs also have stepped up donations, giving Ryan more than $3 million since 2009.

Republican presidential candidate Mitt Romney introduced Ryan as his running mate Saturday in a rollout that highlighted Ryan’s Midwestern charm and small-town roots. But like many top lawmakers, Ryan — who also is seeking reelection to the House — has spent money raised through his political committee to underwrite the expenses common to a Washington power player. He has used donor money for two stays at the Four Seasons in New York in February 2011 and spent $3,600 at a luxury golf resort on an island off the coast of Georgia. Lawmakers are allowed to use money from their political committees for travel and personal expenses.

Brendan Buck, a spokesman for the Romney campaign, said that Ryan’s spending is typical of lawmakers in his position.

Although Ryan chairs the House Budget Committee, that is less likely to explain his popularity among donors than his emergence as an ideological leader of House Republicans devoted to reducing the size of government.

“I don’t think he’s attracting money because he’s chairman of the Budget Committee,” said Jan Baran, a longtime Republican campaign lawyer. “That has never been known as a money magnet. Congress hasn’t even passed a budget in years.”

But Ryan also serves on the House Ways and Means Committee, which has jurisdiction over tax policy, a topic of keen interest across the corporate world.

His largest source of money is Wisconsin-based Northwest Mutual, a life insurance company whose employees and PAC have given Ryan $121,000 over his career. The second-largest source is Koch Industries, a chemical conglomerate owned by two billionaire brothers known for their generosity to conservative causes.

Ryan is well-rooted in Washington, having run for the House in 1998 after having worked as a Capitol Hill aide and at a D.C.-based advocacy group. His wife, Janna, was a registered lobbyist for three years at two Washington lobbying firms, representing clients such as the Cigar Association of America and the Blue Cross Blue Shield Association, which represents health insurers.

A number of Ryan’s supporters are based in Wisconsin and have connections to the construction industry that the Ryan family has worked in for more than a century.

Ryan also has benefited from family contributions, and he made a personal loan of $14,000 to his first campaign. According to his financial disclosure statements, Ryan and his wife have assets between $2.1 million and $7.8 million, with the bulk coming from a trust created after her mother died in 2010. Janna Ryan also holds timber and minerals rights through companies based in Oklahoma, where she grew up.

Paul Ryan has raised money at fundraisers held by lobbyists and others with a web of political and corporate connections, according to invitations collected by the Sunlight Foundation.

In July 2010, for example, a dinner was held for Ryan at Acadiana, co-sponsored by former Republican congressman Jim McCrery (La.), a former ranking member on the Ways and Means Committee. He is now a Washington lobbyist with clients in industries such as banking, health care and petroleum.

In June 2010, a fundraiser for Ryan was scheduled at the Washington office of Humana, a health insurance giant. Among the co-hosts was the PAC for Associated General Contractors, a key construction group.

Brian Turmail, a spokesman for the group, said it co-hosted the fundraiser because members like Ryan’s push to reduce taxes and regulatory burdens on contractors and other businesses.

“There is a sense that the congressman understands the unique challenges facing contractors because, yes, he comes from a construction family,’’ Turmail said.

Ryan’s political committee, Prosperity PAC, drew $4.3 million in this election cycle, compared with less than $1 million in 2010.

As it has grown, Ryan’s PAC has given less money to other lawmakers, the primary reason most members form a “leadership PAC.” Ryan’s PAC put 25 percent of its overall spending toward other Republicans in the 2012 cycle, compared with 64 percent in 2010. Instead, Ryan spent much of his money raising money, with more than $2 million going toward telemarketing and mail. Those expenses help him build a list of donors and national clout.

“That’s how members use leadership PACs — it’s another platform to build their own profile, either with their colleagues in Congress or around the country,” said Robert Kelner, a Republican campaign lawyer.

Ryan’s PAC also has paid for his political trips, with $148,000 in travel expenses. Ryan has reimbursed himself for $69,000 in expenses from his campaign and political committee, including $396 for Christmas gifts and $11,000 for mileage on his car.

Alice Crites contributed to this report.