RICHMOND, Va. — While the Obama administration and Congressional Republicans fight in Washington over cutting a small slice of the federal budget, deficit hawks from both parties have taken to the road to persuade the public that the only way to really fix the nation’s finances is to shrink the growth of popular entitlement programs and to raise revenues.

Two senators — Mark Warner, Democrat of Virginia, and Saxby Chambliss, Republican of Georgia — held an unusual bipartisan forum here on Monday before an overflow crowd of more than 200 Virginia business leaders. They will hold a similar event next month in Atlanta.

While the senators made their pitch for a far-reaching debt-reduction plan requiring some sacrifice from all Americans, including businesses, the co-chairmen of President Obama’s bipartisan fiscal commission — Alan K. Simpson, a former Senate Republican leader from Wyoming, and Erskine B. Bowles, a chief of staff to President Bill Clinton — were speaking in New York, stepping up their campaign to keep alive the recommendations of the commission’s majority in December to cut the debt by $4 trillion through 2020.

To that end, on Tuesday Mr. Bowles and Mr. Simpson will be on Capitol Hill to announce a nonprofit organization, the Moment of Truth Project, which will seek to educate the public as well as lawmakers about the scale of tax and spending changes needed. While the White House is aware of their efforts, officials say the administration has neither discouraged nor encouraged them.

Separately, Mr. Warner and Mr. Chambliss will continue working privately with four other senators — two from each party, all of them former members of the Bowles-Simpson commission — to write legislation based on the panel’s recommendations.

Such efforts face a hard slog not only on Capitol Hill, but also among the public. Polls consistently show that Americans want the White House and Congress to rein in the mounting long-term federal debt. Yet by large majorities they oppose many specific proposals to reduce the future costs of Medicare and Medicaid and to ensure Social Security’s long-term solvency.

In their remarks here, Mr. Warner and Mr. Chambliss acknowledged the hurdles but insisted that Americans were ahead of their elected officials in being ready to take the necessary steps. And they separately criticized the positions of many in their own parties.

While Republicans are adamantly antitax, Mr. Chambliss said, “We’ve got to close the revenue gap.”

And Mr. Warner said Democrats in Congress would have to be willing to further restrain Medicare and Medicaid and to reduce projected Social Security benefits for future generations, perhaps by raising the retirement age over a period of decades, to protect the program’s long-term viability.

“For a Republican to put revenues on the table is significant,” Mr. Chambliss said. “For a Democrat to put entitlements on the table is significant.”

Both men criticized the current negotiations between the Obama administration and Congress for cutting only from the so-called discretionary domestic spending that makes up 12 percent of the federal budget. Republicans have proposed $61 billion in cuts for the balance of the current fiscal year, slashing education, law enforcement, energy programs and more, while the White House and Democrats have countered with a plan for cuts of $10.5 billion.

“If we cut all of that” part of the budget, “we still couldn’t solve the problem,” Mr. Chambliss said.

Reducing entitlement programs, which make up more than 40 percent of the budget, would also not be enough for long-term solvency, he added, “and you can’t raise taxes enough to get us out of this problem. So obviously you have to have all three of those issues up for dialogue.”

A questioner pointed out the importance of military spending in Virginia, home to the Pentagon, bases and shipbuilding, but Mr. Warner and Mr. Chambliss agreed that it must be cut, too.

Mr. Warner echoed Mr. Obama in arguing that much of discretionary domestic spending amounted to government investments. He cited the National Institutes of Health, education and research programs.

He and Mr. Chambliss urged the business leaders to support the deficit-reduction effort. Like the fiscal commission’s majority, they propose to overhaul the tax code to eliminate some of the more than $1 trillion in annual tax breaks for individuals and businesses, and to use the revenues both to lower tax rates and to reduce deficits.

“That simpler tax code means a lot of the current exemptions are going to have to go bye-bye,” Mr. Warner said.

Yet underscoring the political difficulty, the senators declined to say when or if their group might agree to compromise legislation.

“We won’t be able to” agree on everything, Mr. Chambliss said. The goal, he added, is to agree on concepts for tax and spending changes that leave the details to the Congressional committees with jurisdiction. Beyond the six members, he said, 25 other senators are potential allies.

Even if the senators do reach agreement, the chances remain slim that Congress will act, especially in the House. The Republican leaders there have scores of new members, many of them Tea Party adherents little inclined to compromise with Democrats.

Separately, the chairman of the House Budget Committee, Representative Paul D. Ryan, Republican of Wisconsin, is conducting his own classes for freshman lawmakers to educate them about the need to tackle entitlement programs as well as discretionary spending. Mr. Ryan was a member of the fiscal commission but voted against its recommendations because they did not cut health spending enough, in his view, and raised revenues.

But the Senate bipartisan group believes its efforts could gain strength should the White House and Republican leaders reach an impasse this year that threatens an economic crisis.

Mr. Chambliss conceded that any plan would go nowhere without buy-in from the White House and House Republicans leaders. He said that he spoke regularly with Speaker John A. Boehner, a close friend, and that White House officials were also monitoring the group’s talks.

“There are at least conversations going on between all three of us,” Mr. Chambliss said.