The Republicans looking to unseat President Barack Obama want to explain to voters in this early nominating state how they would bring back the nation's crumbling manufacturing core and rebuild the struggling U.S. economy.

A Tuesday forum in Pella, Iowa, is set to give many of the presidential contenders an opportunity to outline their criticisms of Obama and preview their head-to-head pitch should they win the GOP's presidential nomination.

Texas Gov. Rick Perry, looking to Iowa to steady his campaign after stumbling in recent weeks, planned to tout his role in keeping jobs growing in his state during the recession.

Also attending the event, hosted by Gov. Terry Branstad, are former House Speaker Newt Gingrich, former Sen. Rick Santorum of Pennsylvania, and Reps. Michele Bachmann of Minnesota and Ron Paul of Texas.

However, two central figures to the race have decided to skip it: Herman Cain, the Georgia businessman who tops a respected Iowa poll released over the weekend, and former Massachusetts Gov. Mitt Romney, who is essentially tied with Cain here.

Cain spent Monday in Washington, answering questions about why a trade group he once led paid to settle sexual harassment complaints against him. He planned another day in Washington on Tuesday, trying to quiet concerns that could drag down his meteoric rise in polling.

Aides to Romney, the successful venture capitalist who pitches himself as the best opponent to Obama on the economy, said he had a scheduling conflict that prevented him from joining. Romney planned to return to the campaign trail Thursday in New Hampshire.

Without that pair, the event seemed more an opportunity for the GOP's second tier to make a pitch while honing attacks on Obama _ and probably on each other. The rivals are not set to face each other directly, yet the new sense of urgency in the campaign is likely be on display as each seeks to distinguish himself or herself just two months before Iowa's Jan. 3 caucuses.