Gov. Scott Walker in 2016? He draws biggest applause at Iowa summit

For Republicans, the long road to the 2016 presidential election began in earnest on Saturday in Iowa when a group of potential candidates jockeyed for support among conservatives in the state that will hold the country's first nominating contest.

One message that emerged at the Iowa Freedom Summit, a day of back-to-back speeches about eight potential Republican candidates, is that establishment names Jeb Bush and Mitt Romney have some work to do to gain support of grassroots activists should they decide to run.

Perhaps the warmest reception was given to Wisconsin Governor Scott Walker, who survived a recall attempt over his conservative policies in 2012 and won re-election in November.

He drew a standing ovation when he made clear he is seriously considering a White House run in 2016 by vowing to come back "many more times in the future" to Iowa.

He was withering in his criticism of President Barack Obama for not attending a march of world leaders in Paris two weeks ago to show solidarity for the French after attacks there.

"We need leaders who will stand with our allies against radical Islamic terrorists," Walker said.

"I've won the race for governor three times in the last four years. Three times, mind you, in a state that hasn't gone Republican for president since I was in high school more than 30 years ago. How about that. You see, I think that sends a powerful message to Republicans in Washington and around the country that if you're not afraid to go big and go bold you can actually get results." 

When New York developer and celebrity Donald Trump declared to the audience that Romney, the 2012 Republican nominee, cannot be allowed to run a third time and that former Florida Governor Bush is weighed down by concerns about his education and immigration policies.

"You just can't have those two," Trump said.

His statement was predictable, coming from a showboat billionaire who says he is considering his own White House run, and that this time he is serious.

But the reaction from the crowd was noteworthy. Many in the room applauded and cheered at the idea that Romney and Bush should not run. Neither man attended the forum.

Of the possible candidates attending, another big name to watch was New Jersey Governor Chris Christie.

Christie is viewed skeptically by many conservatives, and how he crafts his message here could be critical.

A variety of other people appearing at the forum could emerge as major 2016 players, such as former Texas Governor Rick Perry, who sought the nomination and lost in 2012, and former Arkansas Governor Mike Huckabee, who won Iowa in 2008 but lost the nomination.

Texas Senator Ted Cruz will also speak along with former Hewlett-Packard Co Chief Executive Officer Carly Fiorina and former Pennsylvania Senator Rick Santorum.

Besides Bush and Romney, steering clear of the event were Florida Senator Marco Rubio and Kentucky Senator Rand Paul.

Iowa holds the first nominating contest of 2016 when Republicans and Democrats gather early next year for caucuses. Republicans here have not picked the eventual nominee since they went for George W. Bush in 2004. But the caucuses serve a valuable role in winnowing the field. (Additional reporting by Amanda Becker in Washington; Editing by Lisa Shumaker, Rosalind Russell and Leslie Adler)