Democratic Party leaders have spent weeks preparing a national convention this week that will burst with symbols of unshakable unity behind Senator Barack Obama.

But outside the convention arena in Denver, some of Hillary Clinton’s supporters plan to air their grievances against Obama, the party’s leadership, and the national media, whose coverage of the primary battle they considered sexist. Hundreds of disaffected Democrats from around the country plan to converge in the Mile High City to hold news conferences, protests, and vigils, threatening the party’s ability to present a united front against Republican John McCain.

Many Democrats say the success of the convention, and of Obama’s fall campaign, depends heavily on how well the party handles the complaints of Clinton’s loyalists, some of whom are still smarting from the long and bitter fight, are disappointed that she is not Obama’s running mate, and are insulted by reports that she was not vetted as a possible pick or consulted about his choice.

While many Clinton delegates say they will back Obama and do not intend to embarrass him, grass-roots activists planning protests outside the convention hope to disrupt the sense of unity party leaders are cultivating.

Puma PAC is among a multitude of pro-Clinton groups that formed online to protest a variety of issues, including perceived media bias and flaws in the primary process. In Denver, Murphy’s group plans to show the premiere of an unfinished movie, “The Audacity of Democracy,” and is cosponsoring a protest and candlelight salute to Clinton tomorrow. Another group, PUMA 08, will coordinate communication between its members and the press, and provide a home base for bloggers who support Clinton.