Mayor Cory A. Booker of Newark, a platform committee chairman, emphasized its call for a “balanced approach” to deficit reduction, including raising taxes on the wealthy. “When your country is in a costly war, with our soldiers sacrificing abroad, and our nation is facing a debt crisis at home, being asked to pay your fair share isn’t class warfare,” he said. “It’s patriotism.”

The Democratic platform sometimes reads more like a look back than a road map of what the party would do over the next four years. Many paragraphs are devoted to putting President Obama’s record in the most flattering light possible. The platform mentions that 4.5 million private-sector jobs have been created in the United States since “early 2010” — a time period that ignores the steep job losses of 2009. If the platform had started counting in January 2009, the month Mr. Obama took office, it would have found that 332,000 private-sector jobs had been created.

Some of this year’s planks are reminders of the unfulfilled pledges from 2008.

That platform, echoing a promise Mr. Obama had made as a candidate, said, “We will close the detention camp in Guantánamo Bay, the location of so many of the worst constitutional abuses in recent years.” As president, though, Mr. Obama has failed to deliver on that promise, so the 2012 platform says “we are substantially reducing the population at Guantánamo Bay.”

The 2008 platform called for “comprehensive immigration reform,” but since it has not passed, the 2012 platform does, too. And the 2008 platform said “we will implement a market-based cap-and-trade system to reduce carbon emissions by the amount scientists say is necessary to avoid catastrophic change.” Since that has not happened, the 2012 platform calls for reducing carbon emissions domestically “through regulation and market solutions.”

But any tension between the party’s last platform and its current platform pales in comparison with the differences between the Democratic and Republican party platforms this year.

While the Democrats failed to enact the promised climate change legislation, they still call it a top priority. “We know that global climate change is one of the biggest threats of this generation — an economic, environmental and national security catastrophe in the making,” their platform says, adding that they “affirm the science of climate change.”

This year’s Republican platform dropped the 2008 section on “addressing climate change responsibly.” The new platform states that it opposes “any and all cap-and-trade legislation.”