In addition to revamping entitlements, the Bowles-Simpson plan would cut defense spending.
While opponents say that would weaken the nation's ability to defend itself, the two men argue that the United States currently spends more on defense than the next 15 largest world powers combined.
Much of that is not for traditional national defense.
"I personally believe America is bearing a disproportionate responsibility for world peace," Bowles said. "America has a treaty with Taiwan that we'll protect them if China invades. There's just one problem; we'll have to borrow from China to do it - it's crazy."
Simpson said defense spending has doubled over the past decade and most of the increase has gone to private contractors, not the military.
"(President Dwight) Eisenhower was absolutely right," Simpson said. "He said watch out for the military-industrial complex, they will eat up the whole system."
Because most of the revenue to be generated under the plan comes from closing tax loopholes, Bowles said it also would cut tax rates for many Americans.
He said those making under $70,000 a year could pay an 8 percent rate; those making $200,000 or less would pay 14 percent; and the top marginal rate would top out at about 23 percent.
Although some have argued that ending tax credits could hurt middle class taxpayers, Simpson and Bowles said only about 27 percent of taxpayers even itemize deductions on their tax returns. They said the impact would be minimal.
While he was unable to attend Monday's forum, Sen. Jay Rockefeller, D-W.Va., released a statement later Monday saying while he liked some ideas in the Bowles-Simpson approach, he did not agree with the large amount of cuts.
Rockefeller said 80 percent of the $4 trillion in savings the men project would come from government program cuts while only 20 percent would come from additional revenue.
"My view is that the burden needs to be shared much more equitably - at least 50-50 - because it's neither effective nor fair to cut programs that children, seniors and families build off - from education and job training to transportation, law enforcement and basic health care - unless we are also closing tax loopholes and demanding that the very wealthy go back to paying a reasonable share," Rockefeller said.
Both Simpson and Bowles acknowledged it is a struggle to get support for any type of revenue increases.
Simpson blamed Americans for Tax Reform founder and Washington lobbyist Grover Norquist for much of that. Norquist has enlisted about 95 percent of Republicans to sign a pledge against raising taxes.
Simpson said Republicans are too afraid of running afoul of Norquist to consider revenue increases.
"He can't murder you; he can't beat you," Simpson said. "The only thing he can do to you is beat you for re-election . . . if that means something more to you than being a patriot and doing something for your country, then you shouldn't be in Congress."
While neither wholly agreed with the Simpson-Bowles approach, both Capito and Manchin said they were optimistic Congress could work out a deal on something like it to reform the nation's finances.
Simpson and Bowles said they've raised $30 million for a political action committee that would provide a defense for those who stand up to support the plan. They hope Congress can begin acting on their ideas during a post-election session later this year.
Contact writer Jared Hunt at jared.h...@dailymail.com or 304-348-5148.