There’s no letup in the brawl between Democratic presidential front-runners Sen. Bernie Sanders and former Vice President Joe Biden over the former’s repeated claims that Biden years ago pushed to make cuts to Social Security.

The fireworks began in earnest on Saturday and flared once again the past 24 hours.

Biden tweeted Tuesday evening that “I've been fighting to protect — and expand — Social Security for my whole career. Any suggestion otherwise is just flat-out wrong.” His tweet linked to a Biden campaign video that argued: "Bernie's campaign is not telling the truth. … Bernie's negative attacks won't change the truth: Joe Biden is still the strongest Democrat to beat Donald Trump."

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And the former vice president, in an interview Wednesday on MSNBC’s "Morning Joe," again spotlighted that he has “a 100 percent rating from the groups that rate Social Security.”

For over a week, the Sanders campaign has been pushing an old C-SPAN clip of then-Sen. Biden, of Delaware, saying on the Senate floor, “When I argued that we should freeze federal spending, I meant Social Security as well.”

On Tuesday evening, Sanders tweeted: "Let’s be honest, Joe. One of us fought for decades to cut Social Security, and one of us didn’t. But don’t take it from me. Take it from you." He posted a digital video featuring the audio of Biden discussing the Social Security freeze.

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Fox News’ Andrew Craft was there on Wednesday when the senator – speaking to reporters outside his Senate office – reiterated that “Joe Biden has been on the floor of the Senate talking about the need to cut Social Security.”

Biden countered that his comments had been taken out of context.

While defending himself on Social Security, the former vice president also dinged Sanders over his past record on efforts to combat gun violence and his votes against a background check bill more than 20 years ago.

Talking about the Sanders campaign’s spotlight on his own words from years ago, Biden said: “It's like my going back and pointing out how Bernie voted against the Brady Bill five times while I was trying to get it passed when he was in the House.”

The response from Sanders: “Biden wants to look at my record that's fair. I will look at his record. We'll have that debate.”

Biden wins today’s round in the fight for union endorsements

Fox News’ Madeleine Rivera reports that the former vice president on Wednesday landed the endorsement of the International Association of Bridge, Structural and Ornamental Iron Workers. The 130,000-member union emphasized that a Biden administration would “invest heavily in transportation infrastructure and manufacturing across the country.”

Biden, Sanders and Sen. Elizabeth Warren of Massachusetts are considered the top contenders for union endorsements. Sanders recently grabbed the backing of SEA/SEIU 1984, one of the most influential unions in New Hampshire, which holds the first primary in the White House race, and by a Communications Workers of America local in California, the biggest state to vote on Super Tuesday, March 3.

A two-person race?

Two new national surveys released Wednesday point to the race for the Democratic presidential nomination turning into a two-candidate battle between Biden and Sanders. Sanders stands at 27 percent among Democrats and independent voters who lean toward the Democratic Party in a new CNN poll, with the former vice president at 24 percent. Sanders’ 3-point advantage is within the survey’s margin of error – but the new poll marks the first time Biden hasn’t held a solo lead over his 2020 Democratic nomination rivals in CNN surveys. Sanders surged 7 percentage points since CNN’s previous national poll in the Democratic nomination race, which was conducted in December. Biden’s edged down 2 points.

Biden holds a 7-point lead over Sanders in a new Monmouth University national poll that was also released on Wednesday. The former vice president stands at 30 percent support among Democrats and Democratic-leaning independent voters in the survey, with Sanders at 23 percent. Biden’s jumped 4 points from Monmouth’s previous national survey, which was conducted in December. Sanders has edged up 2 points.

Both candidates stand far above the rest of the field in both polls.

Sanders, Warren dismiss Biden-for-Bolton witness swap

Two of Biden’s top rivals for the nomination are shooting down speculation of attempts at a deal that would guarantee that former National Security Adviser John Bolton testifies at the Senate impeachment trial of President Trump in exchange for testimony by Biden’s son Hunter, who held a high-paying position on the board of a Ukrainian energy company.

Fox News' Tara Prindiville reports that the senator from Massachusetts – talking to reporters on Capitol Hill on Wednesday – said, “The whole idea behind a fair trial is you bring in the relevant witnesses. And relevant witnesses here are people who know what Donald Trump did. And what his intent was and what its impact was on our national security and on the security of Ukraine. Hunter Biden doesn’t have anything, any knowledge about that, or any — any bearing on that.”

And Craft reports that Sanders – when asked if he’d support a potential appearance by Hunter Biden – told reporters, “No, I think that that's clearly, that issue has nothing to do with the impeachment trial. Trump is being charged with abuse of power and obstruction of justice. Those are the issues. Those are the witnesses that need to be called and that's the kind of debate that needs to happen.”

Will Bloomberg price out rivals in Super Tuesday states?

Bloomberg has dished out a massive $248 million to run commercials since declaring his candidacy for president in late November, according to the latest data from the ad-tracking firm Advertising Analytics. That’s far ahead of fellow billionaire Tom Steyer. Since launching his White House bid in July, the former hedge fund manager-turned-environmental-and-progressive-advocate has dished out $134 million for ads. By comparison, no other candidate in the Democratic presidential primary field has topped $30 million in spending.

Since he jumped into the race extremely late, Bloomberg’s skipping Iowa, New Hampshire, Nevada and South Carolina -- the four early-voting states that kick off the nominating calendar in February. Instead, he’s concentrating on the delegate-rich Super Tuesday states that vote on March 3 and beyond.

That means to date, Bloomberg’s TV ads are mostly not in competition with the commercials of his rivals' campaigns that are running in the early-voting states. But in a couple of weeks, as Bloomberg’s rivals turn their attention to the Super Tuesday contests, the former New York City mayor’s massive ad buys will begin to present a problem.

“It will definitely present an issue for other campaigns,” Advertising Analytics account manager Ben Taber pointed out. “He cannot buy up all the inventory, but his massive buys can and are increasing rates. This will make it even more difficult for other candidates to disseminate their messages, as they will be getting fewer airings per dollar spent.”

Gabbard slaps Clinton with $50M defamation suit

Democratic presidential candidate Rep. Tulsi Gabbard of Hawaii is accusing former Secretary of State Hillary Clinton of deliberately spreading false accusations that Gabbard is a Russian asset in a lawsuit seeking upwards of $50 million in damages. During an October 2019 interview with the podcast Campaign HQ With David Plouffe, Clinton suggested the 2020 presidential candidate was "the favorite of the Russians" and "a Russian asset." Gabbard insists these statements have no grounds in reality and that Clinton knew or should have known this at the time.