WASHINGTON (JTA) — Bernie Sanders said it was “imperative” to elect Jon Ossoff congressman from Atlanta’s suburbs, pushing back against the perception that Sanders was unenthusiastic about what is seen as a critical election targeting the policies of President Donald Trump.

“Let me be very clear,” Sen. Sanders, I-Vt., said Friday in a rare email to reporters from what was his presidential campaign account. “It is imperative that Jon Ossoff be elected congressman from Georgia’s 6th District and that Democrats take back the U.S. House. I applaud the energy and grassroots activism in Jon’s campaign. His victory would be an important step forward in fighting back against Trump’s reactionary agenda.”

Sanders, who last year ran an insurgent primary campaign for the Democratic nomination before losing to Hillary Clinton, is on a tour of the United States with the Democratic National Committee to promote party unity.

However, reports of differences between Sanders and the Democratic establishment have dogged the tour, with Sanders insisting that the party’s overarching emphasis must be income inequality.

Last week Sanders, asked about Ossoff by the Washington Post, said of the candidate, “He’s not a progressive.”

That sparked a social media uproar and reopened wounds for backers of Clinton, who said Sanders’ bid had wounded Clinton and that he did nor work hard enough to elect Clinton after Sanders bowed out.

Ossoff received over 48 percent of the vote in an April 18 special election in the 6th District, which has skewed markedly Republican for decades. He beat his closest Republican rival by 30 points and now faces a runoff on June 20.

Ossoff’s surprisingly strong showing is attributed to Trump’s low popularity in the district, even among Republicans. He has endeavored to strike a moderate tone to appeal to disaffected Republicans. Democrats are deeply invested in the district, hoping to strike a blow against Trump and create a momentum that would lead to congressional wins in 2018.

Sanders is the first Jewish candidate to win major-party primary contests. Ossoff also is Jewish.