"It's what happens in Congress that will determine our message more than anything I say or what they say in Congress," Dean said, adding that Democrats must work in the coming year to prepare for the 2008 elections.
Later in the day, a Democratic National Committee rules panel gave preliminary approval to a plan to give bonus delegates to states that hold their presidential contests in April 2008 or later. That plan is intended to discourage states from jamming up the early weeks of presidential voting by moving their contests up.
Democrats, who will run both the House and Senate come January, have outlined an agenda that includes overhauling ethics, raising the minimum wage and making college more affordable.
Dean said Democrats must prove to people in conservative and swing districts that they can earn the voters' trust.
"Elections are not mandates. Elections are power being loaned to politicians for a two-year period by the voters of this country," Dean said. "Now it's our job to earn it back again in '08."
That approach is critical if Democrats are to build on their majority in Congress and retake the White House in 2008, said Dean, who said Democrats did well in November because they appealed to all types of voters.
"George Bush made a huge mistake by representing half of America, while treating the rest of us with contempt," Dean said. "We need to reach out to everybody whether they agree with us or not."
Republicans rejected Dean's view.
"We have already learned the Democrat agenda of raising taxes and surrendering key fronts in the war on terror," said Republican National Committee spokesman Danny Diaz. "Republicans over the next two years will focus on holding Democrats accountable and recommitting to reforms that deliver for hardworking families."
Dean said he was pleased that Democrats drew more support than in the past from "faith voters." Democrats gained among religious voters, including those considered evangelical Christians, because they talked about their values and competed in all parts of the country, Dean said.
Members of the Democrats' rules panel gave preliminary approval to an incentive system of bonus delegates to the party's national convention to persuade states not to move their presidential nominating contents too early in the 2008 calendar.
Under the plan:
The idea is to discourage jamming the primary calendar after moving up Nevada and South Carolina into the first wave of contests to increase diversity in voting. The full Democratic National Committee will consider the bonus plan at their winter meeting in Washington.
Jim Roosevelt, co-chair of the rules panel, said the incentive plan could cause enough big states to hold contests later and keep the presidential competition going until late spring. Some states are already mulling moving their contests up, however.
Two Democrats who defeated Republican incumbents in House races this year told Democratic leaders that the party's commitment to candidates around the country was crucial.
"We have to quit seeing these things as David and Goliath fights and start seeing them as opportunities," said Tim Walz, a high school geography teacher who beat GOP Rep. Gil Gutknecht in Minnesota. "We have the opportunity to extend this to policy and in two years we can extend our majority. There was no controversy to how this was done. It was a great use of resources."
Nancy Boyda, who defeated GOP Rep. Jim Ryun, R-Kan., said, "The difference in organization and execution (between the two parties) was so marked, it was startling."