Hillary Clinton's account retweeted him.
And Marshall, 36, also appeared with Mo Ivory, a popular cable TV personality who hosts a show on Howard University's radio station, to tell her more.
"First and foremost, I'm from St. Louis, so that hit home...I'm just glad that people got together, students stood up, made a statement for what they believed in," Marshall said. "They made their voices heard, and for everything that's going on, we have to make sure their voices are heard in this process and as you see, when people ban together it can be a powerful message."
Presidential candidates --- including Clinton --- have struggled at times this year with race issues, ranging from the fallout of Ferguson, to the church shooting in Charleston and the emergence of the Black Lives Matter movement.
Marshall, whose official title is director of states and political engagement, is the highest-ranking African-American staffer on any presidential campaign. While his portfolio is broad, spanning the 50 states, one of his most important tasks is helping the Clinton campaign navigate a cultural and political terrain that includes a new and boisterous civil rights movement, viral racial incidents and the waning tenure of the nation's first black president.
It was Marshall who Clinton reached out to the morning after nine African-Americans were gunned down in their Charleston church to say how upset she was and to ask how she could address the shooting in a way that could be meaningful.
The resulting address, which he helped craft, functioned as Clinton's race speech, her boldest remarks on what she called America's "deep fault line."
He has his hands in nearly every aspect of the operation; he is a longtime friend of Robby Mook, Clinton's campaign manager.
"I don't make the policy but in thinking about how do we amplify African Americans in general, I am definitely at the table," he said in a CNN interview. "Sometimes too much."
Saturday night in Iowa, Clinton will debate her opponents for the second time and the discussion will be centered on the economy and income inequality, issues that have stark racial components, a thread that has tripped up the field at various times. Getting race right in the first post-Obama election --- and connecting with the Obama coalition and "surge voters" while not alienating others -- is crucial to winning the Democratic nomination and the White House. According to exit poll data from 2012, African American voters were solely responsible for Obama's margin of victory in seven states, including Florida, Ohio and Nevada.
Clinton has racked up endorsements from black elected officials across country, rolled out parts of a criminal justice platform, met with Black Lives Matters activists -- who shouted her down in Atlanta recently -- and pushed for expanding voting rights. Marshall, who recently wrote a memo to supporters outlining Clinton's approach, is a veteran not only of Clinton's 2008 campaign, when she failed to connect with African-Americans, but also of both Obama campaigns -- after Clinton lost, he was recruited to join Obama's team.
"He is a cross between a motivational speaker, a reverend, a teddy bear and a targeting and data savant," said Buffy Wicks, who helped bring Marshall over to Obama's 2008 campaign after Clinton dropped out of the race and worked closely with him on Obama's re-election. "That means he is a bit of a unicorn."
From St. Louis to the White House
For Marshall, it all started freshman year at the University of Kansas, when a senior named Kevin Yoder asked him to join his ticket and run for a senate seat. They won, (Yoder is now a Republican congressman from Kansas), and Marshall later became student body vice president. His tenure then, mirrors what he does now.
"I put a focus on minority recruitment and retention and making sure that KU had an infrastructure in place to recruit and retain kids of color," he said. "That taught me a lot about organizing at the time."
Marshall grew up in St. Louis, where his mother retired as a school teacher and his father worked as a custodian after a stint in the military.
"With a mother, dad, two sisters, it was a strong woman household," he said. "To see what HRC did as first lady stood out to me when I was growing up."
He organized for John Kerry in 2004, joined Clinton's campaign in 2007, and then worked on both Barack Obama campaigns. He also served as the national field director for the Democratic Congressional Campaign Committee -- the first black person to hold that role.
He joined the White House staff in September 2013.
Clinton aides credit Marshall with helping to create a diverse campaign team at the state and upper staff level. Of Clinton's 511 staffers, nearly a third are people of color, matching national demographics. Among them are Tyrone Gayle, who directs regional press; LaDavia Drane, the black outreach director and Brynne Craig, the deputy political director.
When Clinton held an event miles from Ferguson, Missouri, shortly after the Charleston shooting, Marshall helped organize it, drawing on his ties from growing up in St. Louis and from his fieldwork days.
For him, Ferguson was personal.
"Watching your city burn on TV and tanks in our neighborhood and going home for that reason. It was real deep," said Marshall, who watched the coverage from his office near the White House. "It was almost as if I was dreaming. Like, is this really happening in this century?"
Other plugged in staffers help Marshall make sure the campaign is tuned in with what people are talking about.
When, for instance, video surfaced of a South Carolina black high school student getting yanked from her chair by a school resource officer, a digital staffer flagged the incident and Marshall coordinated the campaign response.
And ahead of a recent trip to South Carolina, Brynne Craig flagged a recent New York Times editorial by noted black feminist writer Roxanne Gay called "Where are Black Children Safe." Karen Finney, Clinton's strategic communications adviser and senior spokesperson, made sure the piece was on Clinton's radar. On Thursday, Craig tweeted a photo of African-American staffers clad in black with the hashtag #InSolidarityWithMizzou. Clinton's account later re-tweeted the image.
"First and foremost, Marlon is an African-American and I'm an African-American and there are very many of us who are African-American on this campaign, this is the lived reality of African-Americans so we are always aware of it," said Craig, Clinton's deputy national political director. "As a campaign we do work to have these conversations; it's always on the forefront of our minds because they look like us and they could be our cousins or sisters or brothers."
As a White House staffer, the one-time bartender and DJ helped sell two of Obama's legacy initiatives -- the Affordable Care Act and My Brother's Keeper. His organizing experience came in handy as he wrangled stakeholders in targeted cities across the country to push the uninsured to enroll. The effort famously included Obama talking up health care on "Between Two Ferns."
Similarly, Clinton has expanded beyond traditional media to reach out to African-Americans. Last month, she appeared on "Another Round," a BuzzFeed podcast hosted by two black women who have big Twitter followings.
In a recent memo to supporters, Marshall outlined Clinton's months-long efforts to energize black voters, who the campaign hopes will form the same Southern firewall that helped Obama win, effectively boxing out Sanders and Martin O'Malley.
The memo came days after Clinton kicked off "African Americans for Hillary" at Clark Atlanta University, an event that turned raucous after activists interrupted her speech. Flanked by Rep. John Lewis and Atlanta Mayor Kasim Reed, Clinton stood her ground, shouting over protestors who chanted "Black Lives Matter." The crowd of 2,000 -- mostly students -- countered with "Let her talk!" On Monday, in Chicago, she met with the mothers of slain African-Americans, a session in the works for months.
"We have to have all the voices," Marshall said. "Black Lives Matter is a huge part of it and I love that they are raising these issues and using social media in a way that is really galvanizing people and looking at solutions."
Activists are still waiting for Clinton to roll out a complete criminal justice platform--Clinton has been releasing components of her plan, including "banning the box," eliminating the disparity between crack and powder cocaine and increasing federal oversight of police.
Former colleagues recalled during the low points of campaigns -- poor polling, bad press and bad debates -- Marshall was the motivator and encourager, telling staffers to keep the big picture in mind.
"He can bridge the Obama world and the Hillary Clinton world, the old and the young and the black, white, Latino, Asian constituency world," said Michael Blake, a New York Assemblyman who worked on Obama's presidential campaigns. "He has the track record and the experience and the ability to bring in the right people to create a plan that makes sense. But it will be much harder than the Obama election, nobody has any illusions about that."