The progressive advocacy group Working Families Party (WFP), which had initially endorsed former 2020 presidential candidate Elizabeth Warren (D-MA) before she dropped out of the race, endorsed Sen. Bernie Sanders (I-VT) on Monday.

The WFP lamented the end of Warren’s “groundbreaking campaign” in its official endorsement.

“But with the field narrowing and critical contests coming up in the next few weeks, we believe the choice for working families is clear,” the group said. “Bernie Sanders has been a lifelong champion for working people. He wants to make healthcare, housing, childcare and education basic rights, reform our criminal justice system, protect and expand Social Security and take bold action on climate.”

Sanders thanked the WFP shortly after it issued its endorsement.

“Together, we’re going to build a multiracial, multigenerational grassroots movement to sweep Donald Trump out of the White House and transform this country so it works for all of us,” he said in a statement.

Sanders and Warren had competed in the progressive lane of the race before the Massachusetts senator dropped her presidential bid last week in the wake of Super Tuesday, in which she failed to win any states.

Since the end of her campaign, Warren has declined to endorse Sanders or 2020 rival Joe Biden.

“I need some space around this,” she said during a press conference last week. “And I want to take a little time to think a little more.”