Many of the party's new breed are difficult to categorise, writes Denis Staunton in Washington
Montana's new senator, Jon Tester, is an organic farmer who opposes the anti-terrorist Patriot Act but loves his guns and believes marriage should only be between a man and a woman. Indiana's new congressman, Joe Donnelly, is against abortion and opposes giving illegal immigrants the right to apply for US citizenship. He thinks trade agreements should include safeguards to protect the environment and prevent US jobs from moving overseas.
Many Democrats who will enter Congress for the first time in January espouse a similarly eclectic mix of policies that makes them difficult to categorise as either conservative or liberal.
As the party expanded its geographical base in this week's elections, picking up seats in the west, the midwest and the mountainous "interior west", it has also expanded ideologically.
"A lot of these new members realise I think that the old, ideological approach - you're with us or you're against us - the confrontational approach, that doesn't sit well with voters," says Peter Fenn, a political consultant who has worked on dozens of Democratic campaigns since the early 1980s.
Many of the new intake are fervently anti-abortion, a position that was until recently an impediment to advancement within the Democratic party. Many more are economic populists who reject the pro-business, free trade consensus that has dominated both parties since the early 1990s.
Ohio's new senator, Sherrod Brown, has been a fierce opponent of trade deals he believes have bled his state of manufacturing jobs. His 2004 book, The Myths of Free Trade, argues that trade agreements should include incentives to dissuade corporations from outsourcing jobs.
Where Clinton-era Democrats were at pains to stress their business-friendly credentials, arguing that economic growth was the key to universal prosperity, the new breed of Democratic populists are not afraid to bash big business or to argue that greedy bosses are exploiting working people.
"One of the things this election showed was that people really do care about the economy, healthcare reform, education funding. They're very nervous about retirement security," Mr Fenn says.
Some new Democratic congressmen take a tough line on immigration, calling for harsher penalties on firms that employ illegal immigrants and rejecting anything that smacks of an amnesty for the estimated 12 million undocumented aliens living in the US.
Much US media speculation following this week's elections has focused on the difficulties Democratic leaders could face in reining in the ambitions of the party's old liberal lions, such as Detroit congressman John Conyers, who has called for the impeachment of President George Bush.
The new breed of mavericks could, however, present a more formidable challenge to future House speaker Nancy Pelosi and future Senate majority leader Harry Reid. Many of the new intake were elected in districts that have been Republican for years, making them more vulnerable than other Democratic incumbents at the next election.
"I think this debate is going to be a very interesting one. It depends on where you are. Ohio, Michigan, some of those midwest states that are really hurting, there you're going to see that kind of economic populism. In other places I think you're going to see a desire to become more open when it comes to trade and foreign markets," Mr Fenn says.
A test could come next year when Congress will be asked to renew Mr Bush's "fast-track" trade negotiating authority, which allows the administration to conclude trade deals that cannot be amended by Congress. The administration has promised trade partners it will make a final push to agree a World Trade Organisation deal as part of the stalled Doha round of negotiations, but such an agreement would almost certainly involve cuts to US farm subsidies and more access to US markets for foreign agricultural produce and other goods.
Minnesota congressman Collin Peterson, who is expected to become the new chairman of the House Agricultural Committee, is an ardent defender of farm subsidies and his hand could be strengthened by the new shape of the Democratic caucus.
The social conservatism of some of the new Democrats is unlikely to cause much tension, not least because the Democratic leadership will steer clear of such issues as abortion, gay rights and gun control. "I know one or two Republicans were elected this time as social conservatives, but if they think they're going to make hay with a lot of these social issues, I think they're wrong," says Mr Fenn.