- Biden due to attend Iowa fish fry on Sunday hosted by Democratic Sen. Tom Harkin
- Vice president has not said whether he will make a third bid for the White House
- Iowa kicks off early caucus and primary voting for 2016 race
- Biden finished fifth in 2008 Iowa caucuses, but later selected for ticket
Vice President Joe Biden will be in Iowa on Sunday, which will once again trigger speculation he may make a run for the White House in 2016.
Biden will headline the annual steak fry put on by longtime Democratic Sen. Tom Harkin.
The event, which dates nearly four decades, is one of the signature events for Iowa Democrats, drawing top politicians, and it has a rich history of attracting presidential hopefuls.
Biden has not said whether he'll make a third run for the Democratic presidential nomination. He launched unsuccessful bids in 1988 and 2008.
"I can die a happy man never having been president of the United States of America. But it doesn't mean I won't run," Biden said in a July interview with GQ magazine.
As for his timetable, he told CNN Chief Political Analyst Gloria Borger earlier this year that "I haven't made that decision. And I don't have to make that decision for a while."
But a trip to one of the crucial early voting states like Iowa, which kicks off the presidential caucus and primary calendar, sets off alarm bells among political watchers.
There were a number of stories last month when Biden teamed with President Barack Obama at a campaign style event on education in Scranton, Pennsylvania, where Biden was born.
The event didn't go unnoticed by the Republican National Committee, which posted a web video in advance that characterized the rally as the first step in the "Biden 2016 kickoff tour."
At the event Obama praised Biden, noting it was the fifth anniversary of joining the Democratic ticket.
Obama said it was "the best decision I ever made politically."
Until last month, the RNC and pro-Republican groups had been concentrating firepower mostly on former Secretary of State Hillary Clinton.
If she decides to run for the White House again, Clinton would be considered the Democratic frontrunner.
Biden last appeared at the steak fry in Indianola in 2007.
Then a senator from Delaware, Biden shared the stage with Obama, Clinton, Chris Dodd, John Edwards and Bill Richardson.
Biden was supposed to headline last year's fry, but couldn't make it.
Maryland Gov. Martin O'Malley, who's also considered a possible 2016 contender, was the keynote speaker.
Biden aides say he is showing up this year to honor a commitment he made to Harkin, a five-term senator who's retiring after next year.
Speaking with Iowa reporters on Thursday, Harkin said its way "too early to speculate" about Biden's prospects, but he added "Joe Biden's always had good support among Iowa Democrats. He's very popular in a number of areas around the state."
According to local reports, Harkin also said Biden "has a long history of working with Iowa Democrats, so I think that he would find - how should I phrase it? - fertile ground in Iowa if he should choose to run."
Biden finished a distant fifth in the 2008 Iowa caucuses.
The 2014 race to succeed Harkin will be competitive, and a couple of congressional contests in the Hawkeye state will also attract national attention.
"This trip is really about the 2014 election rather than about 2016," Larry Rasky, a longtime senior political adviser to Biden, told CNN.
He pointed to a fundraiser later this month in the nation's capital that Biden is headlining for Jim Mowrer, who's challenging conservative Iowa Republican Rep. Steve King next year, to highlight the vice president's efforts to help elect fellow Democrats in the midterms.
While touting those efforts, Rasky also conceded that "you can stop people from speculating. The vice president obviously hasn't taken 2016 off the table and Iowa's more than a little important."
The White House announced on Thursday that Biden will travel to the Port of Charleston in South Carolina to discuss jobs and infrastructure. Biden is also scheduled to visit the Port of Savannah, Georgia, later that day.
While the visit is an official vice presidential trip, South Carolina just happens to be another crucial early voting state, holding the first southern primary in the race for the White House. This will be Biden's second visit to the Palmetto State this year.
"You don't want South Carolinians to feel unloved," joked Rasky.
Besides visits to the early voting states, another indicator of whether Biden may launch another presidential bid will be his decision on whether to set up a leadership PAC. Such a move could signal that he is taking more of an interest in setting up a possible campaign structure.
A Biden political adviser, who asked to remain anonymous to speak more freely, said that a leadership PAC is "still being mulled over."
Speaking before Biden at the steak fry will be San Antonio Mayor Julian Castro, who's considered a rising young star in the party. Castro, who gave the keynote address at last year's Democratic convention, is also considered a possible 2016 contender.
Biden won't be the first sitting vice president to speak at Harkin's event. RadioIowa news director Kay Henderson points out that Vice President Al Gore was the main attraction at the 1995 and 1999 events, before running for president in the 2000 election.