A senior adviser to Sen. Bernie Sanders Bernie SandersSirota reacts to report of harassment, doxing by Harris supporters Republicans not immune to the malady that hobbled Democrats The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election MORE’s (I) 2020 presidential campaign suggested Wednesday that recent polling, particularly in key battleground states like Iowa, underestimate support for the Vermont senator’s White House bid.

“Pollsters are guessing. And the point is, 'Are they guessing right?' And they’re guessing who’s going to show up in a Democratic primary,” Chuck Rocha told Hill.TV. “That’s easier in South Carolina and New Hampshire because there’s a lot of historical data.”

“When you talk about a microcosm of the electorate, which is Nevada, which is Iowa, it’s hard to get it right,” he added.

Rocha also argued that the Sanders campaign is not focused on polling.

“If you take the establishment in every state ... who always votes in a Democratic primary, we’re doing okay — we’re in the top three with everybody else,” he said. “When you add infrequent voters and new registered voters into any poll, guess who skyrockets to the top? We do.”

Rocha’s comments come after Sanders spent the weekend campaigning in Iowa.

The Vermont senator held rallies in the state alongside Rep. Alexandria Ocasio-Cortez Alexandria Ocasio-CortezOn The Money: Anxious Democrats push for vote on COVID-19 aid | Pelosi, Mnuchin ready to restart talks | Weekly jobless claims increase | Senate treads close to shutdown deadline McCarthy says there will be a peaceful transition if Biden wins Anxious Democrats amp up pressure for vote on COVID-19 aid MORE (D-N.Y.), a first-term progressive lawmaker who rose to prominence as part of a group known as “The Squad.”

A Monmouth University poll released on Tuesday showed Sanders with 13 percent support in Iowa. He trailed South Bend, Ind., Mayor Pete Buttigieg Pete ButtigiegBillionaire who donated to Trump in 2016 donates to Biden The Hill's Morning Report - Sponsored by Facebook - GOP closes ranks to fill SCOTUS vacancy by November Buttigieg stands in as Pence for Harris's debate practice MORE (22 percent), former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE (19 percent) and Sen. Elizabeth Warren Elizabeth WarrenOvernight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds On The Money: Half of states deplete funds for Trump's 0 unemployment expansion | EU appealing ruling in Apple tax case | House Democrats include more aid for airlines in coronavirus package Warren, Khanna request IG investigation into Pentagon's use of coronavirus funds MORE (D-Mass.) (18 percent) among likely Democratic caucusgoers.

Nationally, Sanders places third in the Democratic field with 17.8 percent support, behind Biden with 27 percent and Warren with 20.8 percent, according to a RealClearPolitics Average of polls.

—Tess Bonn