CNN hosts town halls with Sanders, Buttigieg and Klobuchar

Late last December, three months after he suffered a heart attack in Las Vegas, Bernie Sanders released three letters from physicians attesting to his good health.

On Tuesday night, Sanders said that if the public wants any more information about his health, they should join him on the campaign trail, where he keeps a busy schedule.

Sanders argued that the letters, including one from the attending physician at the US Capitol, amounted to a "detailed report" and, when pressed on whether he would release new details, said, "I don't think we will."

On October 1, Sanders was rushed to an urgent care facility following a grassroots fundraiser in Las Vegas after experiencing chest pains. Sanders then was taken to the hospital in an ambulance and remained there for days before returning home to recuperate.

He was back on the campaign trail about two weeks after he initially fell ill.

Dr. Brian Monahan, the Capitol Hill physician, said in a Dec. 30 letter addressed to Sanders, "You are in good health currently and you have been engaging vigorously in the rigors of your campaign, travel, and other scheduled activities without any limitation."

Monahan also more directly addressed the senator's heart health.

"Several of the medications you initially required (blood-thinner, beta blocker) were stopped based on your progress," Monahan wrote. "Your heart muscle strength has improved. You have never had symptoms of congestive heart failure. The heart chamber sizes, wall thickness, estimated pressures, and heart valves are normal. Several 24-hour recordings of your heart electrical activity indicated no significant heat rhythm abnormality."

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Bernie Sanders on Tuesday night sought to fully divorce himself from supporters who have harassed others online and questioned whether anyone who believes in his agenda would attack a union leader.

Top officials at the Culinary Union in Nevada accused Sanders backers of swarming them online after flyers distributed by the union, which said Sanders would "end" their health care, went viral.

Sanders also questioned whether some of the social media comments cited by critics were, in fact, written by his supporters.

He also pointed out that members of his own staff had been the targets of online harassment.

"Talk to the people in my campaign, often the African American women in this campaign, talk to my wife, about the kind of ugly attacks that have come in to us," he said.

On the broader issue, Sanders was -- in his final point on the question -- unequivocal.

“I do not believe in online bullying," he said. "End of discussion.”

Watch the moment:

Bernie Sanders rejected the idea on Tuesday that Donald Trump tweets about him so frequently because the President wants to face him in November.

After CNN’s Anderson Cooper asked Sanders why Trump wants to face him,” Sanders sarcastically replied, “Oh, really?”

Sanders lauded his devout following as the “kind of grassroots movement that we need to defeat Trump.”

“And what Trump understand that is the way he's going to lose is when we have the largest voter turnout in the history of this country,” he added.

Trump and a number of top Republican elected officials and operatives often publicly comment on Sanders, sometimes suggesting that the Democratic establishment is seeking to deny him the nomination because they oppose his more progressive platform. The strategy by Republicans appears to be to pump up Sanders and his supporters as a way to help him gain the nomination because Republicans believe Sanders, who self-identifies as a “Democratic socialist,” would be the easiest general election challenger.

Watch the moment:

Bernie Sanders called Michael Bloomberg's strategy of skipping the first four states "obscene" and said the former New York mayor was trying to "buy the presidency."

The Vermont senator suggested Bloomberg had insulted both voters and the democratic process, noting that all of the other primary candidates had spent months engaging the electorate.

"He said ‘I don’t have to do that, I'm worth $60 billion,'" Sanders said, mimicking Bloomberg. "'I’ll buy the presidency.’”

Sanders also ripped Bloomberg's embrace of "stop and frisk" policing during the billionaire businessman's three terms as mayor.

”His policies humiliated and offended hundreds and hundreds of thousands of people,” Sanders said.

Bloomberg has apologized for supporting "stop and frisk," but his past comments about the practice have added fuel to the controversy surrounding his record.

Sanders will get the chance to face Bloomberg on the debate stage for the first time on Wednesday.

Hear Sen. Sanders' comments:

Bernie Sanders didn’t answer a question about whether he would accept hundreds of millions of dollars in help from Michael Bloomberg if the Vermont senator becomes the Democratic nominee. 

Sanders told CNN’s Anderson Cooper he doesn’t have a super PAC and hasn’t asked for one, but then ignored a question about whether he’d accept Bloomberg’s money. 

Instead, Sanders touted raising seven million individual contributions, averaging $18.15 from a broad base of Americans. 

“There is a point at which money ceases to be significant,” he said. “We will have enough money to run a strong campaign. We will have enough money to defeat Donald Trump.” 

Bloomberg has been self-funding his own presidential campaign, spending hundreds of millions of dollars on advertising alone.

Watch the moment:

The event with Sanders has begun. He will answer questions from CNN's Anderson Cooper.

Tonight's town halls come just days before Nevada voters will head to caucus sites.

In an effort to prevent the same chaos that occurred at the Iowa caucuses, the Nevada State Democratic Party announced new details on changes being made to its presidential caucuses that are focused on calculating and reporting results.

After dropping an app built by the same company whose "coding errors" caused mass confusion in Iowa, the Nevada party created a new tool and consulted with the Department of Homeland Security, the Democratic National Committee and other experts to update their reporting system and two-source reporting verification process.

While the party isn't calling it an app, precinct chairs will use a "caucus calculator" on party-bought iPads to work out viability and delegate results during the caucuses by adding together caucus results and early vote data into the tool. 

On caucus day, voters will be asked to rank their top three to five choices for president on their ballot, which will be scanned at a processing hub and used at their assigned precinct location on caucus day.

The results from early voting will be included in the caucus calculator and on paper to help precinct chairs include them properly.

CNN's town halls come after the Nevada State Democratic Party tweeted that more than 18,500 state Democrats participated in first day of early voting this past weekend. This is a considerable turnout that Democrats celebrated even as some voters voiced concerns over long wait times.

What early voting has been like: Wait times of more than three hours and a lack of volunteers at at least one precinct had some voters worried about the state's caucuses on February 22. The precinct — Palo Verde High School in Las Vegas — had just six volunteers present as of 5 p.m. Saturday. 

Nevada's Democratic Party leadership is hoping a strong early turnout for its caucuses signals a successful showing this weekend.

Why this community can't be overlooked in Nevada:

Want to watch tonight's town halls from 8-11 p.m. ET? Here's how:

The town halls will air on CNN, CNN en Espanol, CNN International, CNN Airport Network, and stream on CNN.com, CNN OTT apps for AppleTV, Roku, Amazon Fire, Samsung SmartTV, and Android TV, and CNN Mobile apps for iOS and Android, CNN's SiriusXM Channels, and the Westwood One Radio Network.