Sen. Bernie Sanders (I-VT) is pushing back against polls showing his support among the Democrat primary electorate is being undercut by Sen. Elizabeth Warren (D-MA), who in recent weeks has jumped into second place behind former Vice President Joe Biden.

Faiz Shakir, the Vermont senator’s campaign manager, sent an email to supporters and press on Monday touting a number of recent polls to argue Sanders was still “the strongest” candidate to beat President Donald Trump in 2020.

“Over the last few days, a spate of polls have shown that Senator Bernie Sanders has a robust voting base and has solidified his standing as the candidate in the strongest position to defeat Donald Trump in the general election,” Shakir wrote.

He dismissed Warren’s rise, writing that “while other competitors have improved,” Sanders still “maintained his second-place position in every national poll, and many state polls.”

“There will be many ups and downs in the polls during this election, but we continue to grow our grassroots movement and that will ultimately power us to victory,” Shakir added.

The email came after a week of polls showing Warren surging to overtake Sanders for second place among Democrat voters. The results have been uniform across national surveys and polls from early caucus states like Nevada.

On Sunday alone, two polls were released showing Warren leading Sanders. One was an 18 state survey, conducted on behalf of CBS News, with Warren narrowly edging out Sanders for second place if the primary were held today.

The other was a poll out of South Carolina, which holds its primary right before Super Tuesday, by Change Research. The poll indicated Warren in second behind Biden and Sanders tied for fourth with Sen. Kamala Harris (D-CA).

Shakir, however, excluded many of those from his email. Instead, the campaign manger only included polls — some conducted by companies that show Warren surging — with Sanders in the lead.

Neither was any mention made of polls showing Warren overtaking Sanders in the delegate rich Super Tuesday state of California or a statistical dead heat for second place between the two in Iowa.

Sanders, who came close to toppling former Secretary of State Hillary Clinton for the 2016 Democrat nomination, had been steadily lodged behind Biden for months. The positioning was believed to be key to Sanders’ victory when the field winnowed into a two-person race. The assumption was in that scenario Sanders would be able to paint the choice between himself and Biden as a battle between the establishment and the grassroots — much like he did in 2016.

Warren, though, has disrupted the plan. In some states her rise has directly correlated to a drop in support for Sanders, likely because the two overlap on economic issues. In South Carolina, according to the Change Research poll, Warren rose nine percentage points since a similar poll was conducted in May. Sanders, on the other hand, dropped by six percentage points.

Shakir did not include either of the South Carolina Change Research polls in his email. He did, however, link to a poll by the group showing Sanders leading Warren for second place — within the margin of error — when voters were surveyed directly on the topic of climate change.

Warren’s momentum was further confirmed on Monday when a poll out of Minnesota showed her overtaking Biden for first place among the state’s primary voters. Sanders, who carried Minnesota by more than 23 percentage points over Clinton in 2016, polled third.