@ewarren/Twitter(LAWRENCE, Mass.) — Senator Elizabeth Warren, a star of the progressive movement and one of the biggest names in a crowded field of White House hopefuls, is expected to officially announce her entry into the 2020 presidential race on Saturday — the culmination of a tumultuous week after new fallout over her claim of Native American ancestry.
Ahead of an event in Lawrence, Massachusetts, which sits about 50 miles north of Boston near the New Hampshire border, Warren teased to supporters that she will make a "big announcement" and shared in a fundraising email Thursday some of the themes powering her planned speech.
It will be "about how we build a future together," she wrote, and having the "power to build something better … together."
A source familiar with Saturday's kickoff event confirmed to ABC News that Rep. Joe Kennedy III will introduce Warren at the event and endorse her presidential bid. The Boston Globe first reported his appearance and forthcoming endorsement.
Other members of the Massachusetts delegation, including Sen. Ed Markey and Rep. Lori Trahan, are also expected to attend. Trahan is planning to endorse Massachusetts' senior senator for president, according to a person with knowledge of the event.
Warren's decision to briefly stop in her home state, before embarking on a campaign swing through the early voting states of New Hampshire, Iowa, South Carolina and Nevada, hyped speculation that Warren was ready to transition her exploratory committee into a full-blown campaign.
But Warren’s claim of Native American heritage has repeatedly been a distraction during her political career and, at times, become a potential impediment to her presidential ambitions. The issue reignited earlier this week after the Washington Post reported that the former Harvard law professor identified as an "American Indian" on a 1986 registration card for the State Bar of Texas.
The disclosure appeared to raise questions about whether Warren used her ancestral identity to get ahead — a claim she says has been investigated.
But the registration card was not an application to the bar and was used for statistical purposes only, a spokeswoman for Warren told ABC News.
Warren insisted to reporters this week: "This is our family story."
Amid this latest scandal, Warren found herself in a familiar position, apologizing for her claim to Native American ancestors dating back up to 10 generations, telling the Post she "can't go back" and change her decision. She added that she was "sorry for furthering confusion on tribal sovereignty and tribal citizenship and harm that resulted."
Warren further apologized before reporters on Capitol Hill on Wednesday for "not being more sensitive to tribal citizenship and tribal sovereignty."
This revelation comes a week after Warren made a personal apology in a phone call to John Baker, the principal chief of the Cherokee Nation, for her decision to take a DNA test last year.
But Warren also conceded that there may be other documents reflecting the same self-identification, leaving herself open to further criticism.
"All I know is during this time period, this is consistent with what I did because it was based on my understanding from my family's stories," she told ABC News.
In October, the Boston Globe reported that a DNA test taken by Warren showed that she had a Native American ancestry — a move that did not appear to quell any criticism about her family tree from one of her staunchest rivals: President Donald Trump.
He has repeatedly challenged Warren to prove her heritage and antagonized her by sarcastically calling her "Pocahontas."
This most recent stumble in the saga over her Native American heritage seemed to disrupt the momentum heading into Saturday’s announcement and has also raised questions about the durability of her soon-to-be-launched campaign as she continues to confront negative headlines.
After first being elected to the Senate in 2012, Warren rose to the highest echelons of the Democratic Party by taking on Wall Street, propping up the middle class and helping create the Consumer Financial Protection Bureau under President Barack Obama after the 2008 financial crisis.
To gear up for her presidential run, Warren first announced an exploratory committee in a Twitter video released just before the new year.
Leaning in on the core policies that have paved a path to prominence, Warren said in the video, released on Dec. 31, "America’s middle class is under attack. How did we get here? Billionaire and big corporations decided they wanted more of the pie and they enlisted politicians to cut them a fatter slice … We can make our economy work for all of us."
"No matter where you live in America or no matter where your family came from in the world," she added, "you deserve a path to opportunity."
Following Saturday's announcement, Warren’s heads to Dover, New Hampshire. As an early primary state — and because of its proximity to Massachusetts and significance as a linchpin in presidential contests — New Hampshire is expected to be key to Warren's campaign.

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