(Reuters) - In the 2016 Democratic presidential competition there is Hillary Clinton and everyone else, all powerful politicians who could make a credible run should she decide not to seek the presidency.

Vice President Joe Biden is at the top of that group, which also includes Maryland Governor Martin O'Malley and Massachusetts Senator Elizabeth Warren. Biden's visit to Iowa on Wednesday for a relatively minor event speaks volumes about his desire to keep his name relevant in the 2016 discussion.

Biden's trip to Iowa, which will hold the first contest in the 2016 Democratic nominating campaign, comes days after Clinton made a splash there at a Democratic fund-raising event sponsored by Iowa Senator Tom Harkin.

Biden will appear at a kickoff event in Des Moines for a tour by "Nuns on the Bus," an organization that highlights the impact of large amounts of corporate money on political campaigns.

"I think his visit is significant because it comes so quickly after Hillary Clinton's visit," said David Yepsen, director of the Paul Simon Public Policy Institute at Southern Illinois University. "She was sending a signal and I think Joe Biden is too."

Biden's consideration of a 2016 run is well known, but it is not lost on anyone at the White House that his path to the Democratic nomination is decidedly uphill should former Secretary of State Clinton run, as most expect she will.

As White House officials see it, Biden is a viable potential candidate with broad foreign policy knowledge who is held in deep respect by President Barack Obama, but most do not envision him challenging Clinton for the nomination.

The polls bear this out. A Reuters-Ipsos poll from May found 52 percent of Americans would vote for Clinton in 2016, compared with 9 percent for Biden.

"Looking toward 2016, Biden's position is only tenable in Clinton's absence," said Ipsos pollster Julia Clark.

Still, there is a need to keep his name alive should the unexpected take place. Biden has appeared frequently before party loyalists this year, attending 32 Democratic fund-raising events leading up to November congressional elections.

In Iowa, Biden has deep roots as a Democrat who twice sought the presidential nomination, in 1988 and again in 2008.

"He certainly has a network in Iowa and he's done a good job with touching base with that network," said Democrat Mike Gronstal, the majority leader of the Iowa State Senate.

Many in the Biden network in Iowa would at least like to see Clinton face some competition in the Democratic primary campaign for the nomination to keep her focused.

"If he runs I'll definitely support him," said Iowa Democrat Sara Riley. "But I do want there to be a good primary. The biggest fear is if she doesn't have a hard primary and all of a sudden she has a hard general election campaign, she's not going to do well."