Republican presidential candidates Mitt Romney and Herman Cain delivered back-to-back speeches this afternoon to a gathering of conservative activists in Washington, D.C., with Cain’s connection to the grass roots on full display.

Despite allegations of sexual harassment now dogging him for a fifth day, the crowd of about 2,000 Americans For Prosperity activists welcomed Cain with a standing ovation and repeatedly applauded throughout a stump speech that has become standard for him on the campaign trail. Cain, a Georgia businessman and former radio talk show host, and his campaign manager, Mark Block, are both AFP veterans.

Romney, using the venue to reveal for the first time his plans to rein in federal spending and reduce the size and scope of government, received polite and periodic applause as he laid out a plan that sounded similar to proposals offered on Capitol Hill by House Budget Chairman Paul Ryan (R-Wis.). The former Massachusetts governor said he would cap federal spending at 20 percent of gross domestic product and reform Medicare and Social Security for younger workers.

“I’m committed to making government simpler, smarter and smaller,” Romney said.

His ability to woo conservative activists such as the ones at today’s event could determine whether he can capture the GOP presidential nomination. Recent polls show Romney in a near tie with Cain nationally, and either tied or slightly behind Cain in some of the key early primary states.

Cain only briefly referenced the sexual harassment allegations. “I’ve been in Washington all week and attracted a little bit of attention,” he said. The crowd responded in laughter.

Meanwhile, Cain made a forceful case for his 9-9-9 tax reform plan, but garnered less applause for that than for his more popular lines about reducing the influence of the Environmental Protection Agency on businesses and injecting business principles into the running of the government. Cain’s overhaul would scrap the current tax code and replace it with a flat income and corporate tax rate of 9 percent, as well as a 9 percent national sales tax.

“Nine, nine, nine takes out the invisible taxes and replaces it with one that I can see,” Cain said.