An increasingly assertive caucus of Mormon Democrats is planning a coming-out party during the Democratic National Convention in Charlotte, N.C. The group, which calls itself “LDS Dems” — LDS for Latter-day Saints – expects to draw about 200 motivated Mormons from around the country at the event, planned for Sept. 4 at a hotel next to the convention arena. Their keynote speaker will be Senator Harry Reid of Nevada, the majority leader and a Mormon who recently accused his co-religionist and the Republican nominee, Mitt Romney, of having paid no taxes for years, without providing any evidence to back up the claim.

Greg Prince, a Mormon businessman and pathology researcher in Washington who is helping to organize the event, said: “It’s not just that Mormon Democrats, particularly in Utah, have been playing defense. They haven’t been playing. Within the State of Utah, they basically conceded the entire active Mormon population to the Republicans.”

Mr. Prince said he donated the maximum to Mr. Romney’s campaign during his last run for president, in 2008, because of his relatively moderate record as the governor of Massachusetts. But Mr. Prince said he became disillusioned as Mr. Romney moved to the right to win the nomination this time. Mr. Prince said he supported a public safety net for the poor and immigration policies that keep families intact – Democratic positions that he said should be a natural fit for Mormons.

A poll by the Pew Research Center released in January found that 74 percent of American Mormons identify as Republican, 17 percent as Democrat, and 9 percent say they are independent or don’t know their preference.