When Senator Clinton announces today that a former governor of Iowa, Thomas Vilsack, is getting behind her campaign, many will be wondering what kind of weight his endorsement will carry in that key caucus state.
Mr. Vilsack, who dropped out of the Democratic presidential field last month, may not be a household name outside Iowa, but he has strong political support in his home state.
One of Mr. Vilsack's biggest backers, Gordon Fischer, a one-time chairman of the state Democratic Party, said if the governor's grassroots organization gets behind Mrs. Clinton, her ground operation will see an instantaneous boost.
"Governor Vilsack has a significant organization, having run for governor twice before and having started to run for president," Mr. Fischer said. "I think he can really help a candidate by loaning or lending his organization. That may be the main benefit."
Mr. Fischer added: "We have 2,000 precincts in Iowa, and there's a caucus in every single precinct. He was way ahead of any other candidate in terms of lining up county chairs and precinct chairs."
A spokesman for Mrs. Clinton, Mo Elleithee, declined to confirm the endorsement. Sources said Mr. Vilsack will be named a national chairman of the campaign in Des Moines today, while his wife, Christie, will be named co-chairwoman of the Iowa operation.
The Vilsack endorsement could deliver the biggest blow to Senator Obama, because Senator Edwards already has a strong Iowa infrastructure from his run in 2004. It could also prompt some of Mr. Vilsack's Iowa staffers to defect to Mrs. Clinton.
The chairman of the political science department at Drake University in Des Moines, Arthur Sanders, said that while Mr. Vilsack is popular in the state, he has always had an "uneasy alliance" with Iowa Democratic activists.
The governor has been credited with helping to re-establish the state's Democratic party, but his work with Republicans on certain issues, including a law that made English the state's official language, did not sit well with many in his party.
"Will it make much difference in terms of the likely outcome of the caucuses? Probably not," Mr. Sanders said of Mr. Vilsack's expected endorsement. "But had he endorsed someone else it would have made it more difficult for Hillary." A new American Research Group poll found that 34% of Iowa Democrats support Mrs. Clinton, 33% Mr. Edwards, and 16% Mr. Obama.