With exactly three weeks to go until the Iowa caucuses, Democratic presidential candidates entered their last-chance debate Thursday in Iowa by calling for the elimination of tax cuts for the wealthy and excessive military spending.

The debate, sponsored by Iowa Public Television and the Des Moines Register, copied the format from the GOP debate Wednesday where candidates were asked to address economic questions foremost, instead of other more contentious topics in the race.

And like with the Republican debate, the event steered clear of the rancor that has come to define the Democratic contest among the top-tier candidates.

One of the few moments where candidates actually interacted came toward the end, when Illinois Sen. Barack Obama was asked how he expects to provide an administration of change when several of his advisers used to work for Bill Clinton.

New York Sen. Hillary Clinton laughed conspicuously, and Obama turned to his rival and quipped: "Well Hillary, I'm looking forward to you advising me as well."

The audience applauded. Obama said he would "gather talent from everywhere" in his administration in order to "change the mindset" that led the country into the Iraq war.

But the debate started with policy-oriented questions about balancing the federal budget. Most of the questions were similar to those asked during the Wednesday debate.

In response, Obama said it would take more than a couple years to balance the budget, but that he would push for fiscal responsibility.

"Over the past seven years what’s we’ve seen is an economy that is out of balance, because of the policies of George Bush and the Republicans in Congress," he said.

Clinton said she would keep middle-class tax cuts but raise taxes for the wealthy and corporations.

Former North Carolina Sen. John Edwards said he wants to eliminate tax breaks for those groups, as he wrapped the bulk of his debate comments around the theme that average Americans need to stand up against corporations and special interests.

"What we ought to be doing ... is getting rid of these tax breaks for big — the wealthiest Americans — big tax breaks for companies that are actually taking American jobs overseas," Edwards said. "This is insanity, when we're losing American jobs at the rate we are today."

Delaware Sen. Joe Biden said he would eliminate tax cuts for the wealthy and cut back special programs for the military, like developing atomic weapons.

"Fiscally responsible budgets I believe are critical for economic growth," said New Mexico Gov. Bill Richardson.

Several candidates also listed ending the Iraq war and its accompanying multi-billion dollar price tag as a key way to balance the budget.

The final face-off before the Jan. 3 Iowa caucuses was a critical opportunity for candidates to rise above the pack in the tightening Iowa race. But initially exhibiting few differences, the Democratic candidates tried to highlight their mutual desire to have universal health care and end the Iraq war. And the candidates showed passionate unity on the issue of global warming and energy policy. They entreated Americans to join an energy efficiency campaign as a new form of patriotism.

"This is a moral imperative," Obama said.

"It's not just enough to have an energy plan, not just enough to attack global warming. We've got to enlist the American people," Clinton said. "We cannot sustain the current energy profile in this country."

Richardson offered several specifics, saying he would reduce oil consumption by 50 percent by mandating a fuel efficiency standard of 50 miles per gallon.

Connecticut Sen. Chris Dodd also participated in the debate. But Ohio Rep. Dennis Kucinich and former Alaska Sen. Mike Gravel were excluded from the event, even though the hosts allowed obscure Republican candidate Alan Keyes, a former ambassador, to participate Wednesday.

The Des Moines Register Web site said Kucinich and Gravel did not meet certain criteria, including having a campaign office in Iowa as of Oct. 1.

Kucinich's Iowa field director operates out of a home office, which apparently doesn't count — Kucinich objected strongly to his exclusion.

"Setting arbitrary Iowa-specific criteria for a debate that will be broadcast all across the nation and around the world is a ruse and a fraud," he said in a statement.

Iowa is a key battleground, as both the Republican and Democratic races tighten and appear to be in a condition of flux in certain early voting states.

Clinton walked into the debate Thursday leading by double digits nationally, but losing her hold on Iowa.

A Strategic Vision poll of 600 likely voters from Dec. 8-10 showed Obama with 33 percent, Clinton with 25 percent and Edwards with 24 percent in the state.

And recent polls from New Hampshire, which holds its primary Jan. 8, show the race in a dead heat at the top.

The face-off Thursday came after Clinton personally apologized that morning en route to the event for remarks made by a top adviser warning Obama that admission of his past drug use could come back to haunt him on the campaign trail.

Despite negative news out of the campaign in recent days, Clinton campaign chairman Terry McAuliffe told FOX News Wednesday that the campaign is not concerned, and is confident of its frontrunner status going into the early primaries and caucuses.

In the GOP debate Wednesday, candidates were prompted to focus on economic issues, education and climate change over more hot-button topics like Iraq, Iran and illegal immigration.

Some GOP candidates complained that the format and moderator did not give the candidates an adequate opportunity to address the major issues.

"I wish I had a chance to discuss (terrorism) at the debate today," Rudy Giuliani said afterward. "One of the things that I found unsatisfying about the debate today was that it cut off discussing Iraq and illegal immigration. They are two of the biggest issues that face us."

Former Tennessee Sen. Fred Thompson's campaign released a statement after the debate saying "Fred Thompson: 1, Debate Format: 0."

During the debate, Thompson refused to engage in what he called "hand shows" after moderator Carolyn Washburn asked how many candidates thought climate change was a serious threat.

Jokingly, Clinton asked Washburn Thursday if she would also like the Democrats to raise their hands to show their concern for global warming.

"It didn't get a very good response from Republicans yesterday ... But we all want to be on record," Clinton said — but the moderator did not ask for a head count.