CEDAR RAPIDS, Iowa — Sen. Bernie Sanders took aim at Democratic primary rival Joe Biden at the Iowa Democratic Party Hall of Fame forum Sunday, declaring that a "middle ground" strategy would change nothing.

"Now I understand there are well-intentioned candidates who believe the best way forward is a middle ground strategy that antagonizes no one, that stands up to nobody, and that changes nothing," Sanders said. "In my view, that approach is not just bad policy, but it is a failed political strategy that I fear could end up with the reelection of Donald Trump."

The former vice president has declined or been slow to support progressive policies champion by self-described democratic socialist Sanders. Biden came under fire from primary rivals and Democratic candidates last week for declining to support repealing the Hyde Amendment, which prohibits federal funds from being used on abortion services. In response to the pressure, Biden reversed his position. He has also declined to support Medicare for All, a single-payer national healthcare plan that would eliminate private insurance.

"The American people want change, they want real change, and we have got to provide that change," Sanders said. "And that means if we believe in Medicare for All as a human right, we must take on the power of the insurance industry. If we believe that we must cut prescription drug costs in half, we must take on the greed of the pharmaceutical industry."

Sanders similarly criticized Biden last weekend at the California Democratic Convention, alluding to Biden's absence at the event. Biden also skipped out on today's cattle call event, where 19 candidates addressed Iowa Democrats.

Other Democratic candidates have criticized progressive stances held by Sanders.

Last weekend at the California Democratic Convention, 2020 hopefuls former Colorado Gov. John Hickenlooper and former Maryland Rep. John Delaney received boos for rejecting progressive positions supported by Sanders. Hickenlooper said that said that “socialism is not the answer” to “beat Donald Trump and achieve big progressive goals,” while Delaney said that “'Medicare for all' may sound good, but it's actually not good policy, nor is it good politics.”