DAVENPORT, Iowa — Sen. Bernie Sanders, in his final campaign swing ahead of the state's caucus, said on Friday, 'to hell' with those who have questioned the plausibility of his radical social and economic agenda.

The socialist now finds himself in a tight race with former secretary of state Hillary Clinton, who once seemed inevitable. Clinton has tried to argue that while she shares many of Sanders' goals, his agenda wouldn't be politically feasible.

But at the outset of his remarks following a rousing introduction from academic Cornel West, Sanders addressed this criticism.

"One of the themes that has been going around in this campaign is what we are talking about — transforming America's political system, transforming our economy, transforming and reforming a broken criminal justice system," he told an energetic crowd packing into the Danceland Ballroom event space.

Then, mocking his critics, he said, "It's just to hard. It can't be done. We have to think much, much, smaller."

But then he interjected, "And I say, to hell with that."

He added, "I get a little tired when you hear establishment folks saying you're thinking too big."

Over the course of the speech, he laid out his agenda that he said would require a "revolution" to be implemented.

His promises include offering free college; subsidized child care; three months of mandated paid leave; a $15 minimum wage; stricter campaign finance regulations; more regulation of big banks; and a massive tax on financial trading.

In the closing days of his Iowa campaign, Sanders was also sure to emphasize a number of issues that are of particular importance within the black community, including incarceration levels and shootings of young African Americans by police officers.

To this point in the campaign, Sanders has struggled to gain the support of black voters. Though the black vote is relatively small in the early voting states of Iowa and New Hampshire, where Sanders has been polling well, blacks make up a much larger percentage of the Democratic primary electorate in later states. This is why Clinton is still considered the odds on favorite to win the nomination no matter what happens here.

By campaigning with West, the prominent black intellectual, and emphasizing more criminal justice reform issues, Sanders is hoping to eat into Clinton's support among this crucial voting bloc to make his candidacy more viable and sustainable.