Even lawmakers most loyal to their leaders and political party on occasion buck them with a flash of independence or bipartisanship. That includes some of the six Republicans and six Democrats given the task of finding up to another $1.5 trillion deficit savings over the next decade.
Such moments offer a glimmer of hope that the deficit-reduction supercommittee members, chosen by their party leaders primarily for their party loyalty, can forge a compromise. If there's partisan gridlock, just one lawmaker, perhaps influenced by a past moment of courage, can break the deadlock.
A simple majority of seven would send a budget-cutting plan to the full House and Senate, and avoid an automatic $1.2 trillion in cuts to hundreds of programs.
"It's not a dozen free spirits," said Ross Baker, a political science professor at Rutgers University who once worked as a Senate staff aide.
Baker, however, said he believes the committee might succeed. "If they drop the ball, it would reflect badly on all of them. They would be 12 individual failures. I don't think they want to be associated with a train wreck."
Often, there's a state or district parochial reason when a party stalwart strays from the leadership or party doctrine.
Sen. Patty Murray, D-Wash., the panel's co-chairwoman, has been ferocious in opposing the Obama administration's attempt to cancel Yucca Mountain in Nevada as a depository for the country's nuclear waste. Her chief Senate rival on that issue is Majority Leader Harry Reid of Nevada, who has worked tirelessly to kill the project but nevertheless named Murray to the deficit-reduction committee.
Keeping the Yucca project alive is a critical issue in Washington state. She said "billions of dollars and countless work hours have been spent" at the Hanford nuclear site in her state -- as well as in other states -- to treat and package nuclear waste that was destined for Nevada. The issue of closing Yucca is now in the courts.
Republican Rep. Fred Upton, from the high unemployment state of Michigan, broke party ranks several times and voted to extend jobless benefits -- even when the spending had not been offset with cuts elsewhere as most Republicans demanded.
And one such vote in 2008 at the depths of the recession, he characterized his break from party orthodoxy as stepping up "on behalf of Michigan's workers to provide a helping hand to those who need it most -- laid-off mothers and fathers who are doing all they can to make ends meet."
Rep. James Clyburn, D-S.C., the highest-ranking African-American in the House, once took on the NAACP over the group's economic boycott of South Carolina.
The NAACP was angry that the Confederate flag was flying outside the state Capitol but Clyburn refused to go along with the sanctions, pointing out that the flag had been removed from atop the building and from the legislative chambers.
Clyburn said he didn't want to do anything that "threatens the economic security of families" and stood his ground when the NAACP asked blacks not to invite him to positions of honor at dinners and other events.
He told an interviewer, in comments that could well serve the deficit committee, "I don't like the location of the flag, but we don't get all we want all the time."
Freshman Sen. Rob Portman, R-Ohio, has worked with Democrats numerous times on issues he believes are important.
He teamed up this year with Democratic Sen. Jeanne Shaheen of New Hampshire on a bill to boost energy efficiency. Portman had a message that also could serve the new committee.
"With the gridlock and partisanship in Washington, it is reassuring to see our legislation move so quickly to the entire Senate, and on a bipartisan basis," he said.
Portman and the Democratic chairman of the Senate Judiciary Committee, Patrick Leahy of Vermont, co-sponsored legislation to improve programs to help state and local authorities reintegrate prisoners into communities. And in his earlier House career, he worked with Democrat Benjamin Cardin of Maryland, now a senator, on legislation to boost Americans' retirement savings.
As a freshman in 1993, supercommittee member Rep. Xavier Becerra, D-Calif., did the unthinkable. At a time when committee chairmen had unlimited power, Becerra had a shouting match with the gruff House Ways and Means chairman, Dan Rostenkowski.
Becerra and the Congressional Hispanic Caucus were furious over Rostenkowski's plan to delay previously budgeted welfare payments to legal immigrants. Rostenkowski's plan won, and insiders told Becerra he would never get a coveted seat on Ways and Means.
Three years later, Rosentowski pleaded guilty to mail fraud and went to prison, and Becerra gained his Ways and Means seat. He's now the ranking Democrat on the Social Security subcommittee.
In 1985, Sen. John Kerry, D-Mass. crossed party lines to become a co-sponsor of the Gramm Rudman-Hollings balanced budget act that imposed a binding constraint on federal spending. He supported deficit reduction laws in 1993 and 1997.
He also has worked well with other Republicans: Lindsey Graham of South Carolina on climate change; Kay Bailey Hutchison of Texas on a proposal for an infrastructure bank to finance roads and other projects; Richard Lugar of Indiana on the latest arms reduction treaty with Russia; and with fellow Vietnam veteran John McCain of Arizona on POW/MIA issues and, more recently, the NATO mission in Libya.
Rep. Chris Van Hollen, D-Md., in 2007 went against some members of his party when he authored a provision that required disclosure of lobbyists' bundled contributions -- donations solicited by the lobbyists and then bundled together for campaign organizations. That proposal became law.
Van Hollen authored House-passed legislation with Republicans calling for Reconstruction Opportunity Zones in Afghanistan. He worked across the aisle on legislation to combat childhood cancer and a bill to protect whistleblowers.
Rep. Jeb Hensarling, R-Texas, the other supercommittee co-chairman, angered Republicans on the Appropriations Committee in 2007 and 2008 when he was chairman of a Republican study committee that demanded more spending cuts.
Hensarling crafted a seven-point strategy for House Republicans that included a constitutional amendment to limit spending and a flat tax on goods and services to replace the federal income tax.
Today, Hensarling doesn't have to take on Republicans over spending. His budget-cutting views are now in the party mainstream.
Rep. Dave Camp, R-Mich., the current chairman of the Ways and Means Committee, went against his leadership in the mid-1990s to help break a logjam that allowed an overhaul of the welfare system to pass.
Senate Finance Committee Chairman Max Baucus of Montana has carried the ball for Democrats on major issues like the health care insurance overhaul, but he's also infuriated his party's leaders by working with Republicans. Democrats were angered when Baucus spent months in an unsuccessful attempt to win Republican support for the health care bill.
In 2001, Baucus partnered with Republican Sen. Charles Grassley of Iowa to support President George W. Bush's first round of tax cuts.
And last December, he voted for the large tax cut deal negotiated between President Barack Obama and congressional Republicans. Many liberal Democrats opposed it. Baucus was on stage for the signing ceremony; most top Democratic leaders were not.
Baucus also helped Republicans pass Bush's Medicare prescription drug coverage plan, angering Democratic leaders who had been excluded from the bargaining.
Yet, when Reid needed an ally to block Bush's plan to partially privatize Social Security, he chose Baucus as the point man to stop the proposal.
And he did.