WASHINGTON >> Hillary Rodham Clinton will end months of speculation about her political future and launch her long-awaited 2016 presidential campaign on Sunday, according to people familiar with her plans.

The first official word that Clinton will seek the Democratic Party’s nomination will come via an online video posted on social media. She’ll then make stops in key early voting states, including Iowa and New Hampshire, where she’ll hold small events with voters.

One Democrat familiar with campaign rollout said Clinton’s stops would include visits to people’s homes in those early states.

The people familiar with Clinton’s plans spoke on condition of anonymity because they were not authorized to discuss them publicly.

The former secretary of state will be making her second bid for president and will enter the race in a strong position to succeed her rival from the 2008 Democratic primary, President Barack Obama. Clinton appears unlikely to face a stiff primary opponent, though a handful of lower-profile Democrats have said they are considering their own campaigns.

Should she win the nomination, Clinton would face the winner of a Republican primary season that could feature as many as two dozen candidates. Among them, Republican Sen. Marco Rubio of Florida, who is expected to formally announce his campaign in Miami on Monday — a day after Clinton’s announcement on social media.

Clinton will return to politics following a two-year leave from government. If elected, the former first lady would be the nation’s first female president.

Republicans have been preparing for a second Clinton campaign since she left Obama’s administration in early 2013. They intend to campaign against her by equating her potential presidency to that of a “third” Obama term, during which they argue she would continue his most unpopular policies.

Clinton’s announcement was preceded by withering criticism over her use of a personal email account and server while she was secretary of state, as well as the Clinton Foundation’s acceptance of donations from foreign governments.

She said at a news conference last month she used the personal email account for convenience. Republicans running a select congressional committee reviewing the 2012 attack on a U.S. facility in Benghazi, Libya, which took place during Clinton’s tenure at the State Department, are investigating her decision to delete thousands of emails she has deemed personal in nature.

By campaigning heavily in Iowa and New Hampshire, Clinton hopes to avoid making the same stumbles against Obama as she did in the 2008 Iowa caucuses, which he won in an upset. Democrats echoed hopes that she would seek personal connections this time.

Davenport, Iowa, Mayor Bill Gluba, a Democrat elected in a non-partisan election who backed Obama in 2008, said Clinton “kind of blew it last time” in the nation’s first caucus state. “She’s a very decent wonderful woman, but sometimes they come out of the New York atmosphere and they’re surrounded by staff and they’re insulated. We don’t want to see that,” he said.

“I’d like to have her come to Davenport and we’ll take a stroll along the Mississippi river and chit chat a little bit and just talk,” said Gluba, who recently had lunch with former Maryland Gov. Martin O’Malley, who is also considering a campaign.

Clinton also sees such campaigning as a way not take for granted her formidable position in the Democratic field.

Among the Democrats who could challenge Clinton in the primary are O’Malley, former Rhode Island Gov. Lincoln Chafee, former Virginia Sen. Jim Webb and Vice President Joe Biden.

In announcing her campaign, Clinton is likely to offer her most specific explanation for why she will seek the presidency again after months of offering glimpses into her rationale, including ways to address the gap between the rich and the poor and providing children and young people with more opportunities.

In a new epilogue released Friday to the paperback version of her State Department memoirs, “Hard Choices,” Clinton writes about the joy of becoming a grandmother for the first time — her granddaughter, Charlotte Clinton Mezvinsky, was born last September — and says it informs her work.

“Becoming a grandmother has made me think deeply about the responsibility we all share as stewards of the world we inherit and will one day pass on,” Clinton wrote in the epilogue, published by The Huffington Post. “Rather than make me want to slow down, it has spurred me to speed up.”

Clinton’s race is expected to cost more than the $1 billion Obama raised for his 2012 re-election and aides have said she is expected to focus heavily on online fundraising. Her campaign will be required to release its first fundraising report in July and it will be closely examined to measure the strength of her support.

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Associated Press writer Catherine Lucey in Des Moines, Iowa, contributed to this report.