HuffPost political reporter Daniel Marans said Sen. Bernie Sanders Bernie SandersSenate Republicans signal openness to working with Biden Hillicon Valley: DOJ indicts Chinese, Malaysian hackers accused of targeting over 100 organizations | GOP senators raise concerns over Oracle-TikTok deal | QAnon awareness jumps in new poll Schumer, Sanders call for Senate panel to address election security MORE (I-Vt.) fell behind former Vice President Joe Biden Joe BidenThe Memo: Warning signs flash for Trump on debates Senate Republicans signal openness to working with Biden National postal mail handlers union endorses Biden MORE in the Democratic delegate race partly because he didn’t have a plan if the moderate vote consolidated around a single candidate.

“To consider the idea that the moderates might consolidate – he never had a plan for that,” Marans told Hill.TV Thursday.

Marans cited other reasons why he believes Sanders is lagging behind Biden, including that the progressive senator “has always been sort of skeptical of traditional campaign tools” such as polling.

Sanders had hired staff that was “relatively new” to the political campaign world, Marans also said, while noting the candidate was hesitant to “go on the attack” against Biden and did not move to consolidate support within the Democratic Party.

“When he was riding high, he did not pivot to sort of welcome in the larger Democratic Party and stop railing against the establishment,” he said.

Marans also mentioned that Sanders praised some of Cuba's Fidel Castro's policies, specifically his literacy plan, leading to criticism from members of his own party.

Sanders won the popular vote in the first three primary states when the moderate vote was split. But following Biden’s win in South Carolina, Sen. Amy Klobuchar Amy KlobucharEPA delivers win for ethanol industry angered by waivers to refiners It's time for newspapers to stop endorsing presidential candidates Biden marks anniversary of the Violence Against Women Act, knocks Trump and McConnell MORE (D-Minn.) and former South Bend, Ind., Mayor Pete Buttigieg Pete ButtigiegBogeymen of the far left deserve a place in any Biden administration Overnight Defense: Woodward book causes new firestorm | Book says Trump lashed out at generals, told Woodward about secret weapons system | US withdrawing thousands of troops from Iraq A socially and environmentally just way to fight climate change MORE dropped out of the race to back the former vice president.

Since then, Biden has climbed in the delegate count to 1,217, while Sanders sits at 914.