Steve Bannon encouraged House Republicans to call former Vice President Joe Biden and his son Hunter to be impeachment witnesses for the GOP.

'I ought to tell you I think two witnesses that have to be called are Hunter Biden and Joe Biden,' Bannon said Sunday on 'Sunday Morning Futures' with Maria Bartiromo. 'Joe Biden is a hand grenade and Hunter Biden's the pin and when that pin gets pulled that shrapnel is going to blow back all over the Democratic establishment,' Bannon added.

On Thursday the House passed a resolution, mainly along party lines, that made the impeachment inquiry into President Trump official and laid out the rules. Among those rules, Republicans are allowed to suggest witnesses, but Intelligence Committee Chairman Adam Schiff and House Democrats have to say yes to them too.

Steve Bannon said Sunday that the Republicans should call Joe and Hunter Biden as impeachment witnesses. House Democrats passed an impeachment resolution Thursday that allows House Republicans to call witnesses, but Dems have to approve them

Hunter Biden (left) and Joe Biden (right) are at the center of President Trump's impeachment drama, as the president is in trouble with House Democrats for asking Ukraine to investigate the Bidens and is accused of withholding aid dollars

Bannon agreed when Bartiromo said she didn't think Schiff would allow Republicans to bring the Bidens to Capitol Hill.

'No, he's not,' Bannon said.

The former vice president is running for the 2020 Democratic nomination.

But he and his only living son are central characters in the president's impeachment drama, as Trump is suspected of holding up military aid to Ukraine as a way to pressure the country into investigating the Bidens.

Hunter Biden sat on the board of a top Ukranian energy company called Burisma.

Joe Biden called for the ouster of a top prosecutor in Ukraine, which Trump has claimed was investigating Burisma.

In reality, a number of American allies encouraged Biden and the Obama administration to push for the prosecutor in question to be gone, as he wasn't doing enough to stop corruption in Ukraine.

Hunter Biden also had business dealings with China while his father was serving as vice president, which Republicans have pointed a finger at suggesting those enganglements are corrupt.

'Joe Biden, this is about him as a Constitutional officer, this is about him as vice president of the United States in Ukraine and in China,' Bannon said Sunday, referencing the two countries where Hunter Biden was doing business.

'He's going to have to answer, I think, to these panels exactly what he did about bringing American crony capitalism to already what is considered one of the most corrupt nations on earth and the most corrupt nation - as the Guardian newspaper says - in Europe,' Bannon said of Joe Biden.

Bannon also floated that two prominent, moderate Democrats are waiting in the wings for Biden to choke.

The former top Trump adviser, who left the White House in August 2017, called attention to Biden's performance at Friday's Iowa Democratic Party Liberty & Justice Celebration in Des Moines.

Steve Bannon (left) told Fox News Channel's Maria Bartiromo (right) that he thought moderate Democrats could pull Mike Bloomberg or Hillary Clinton into the 2020 race if Joe Biden loses steam or Pete Buttigieg doesn't get enough traction

Steve Bannon floated the names of former New York City Mayor Mike Bloomberg (left) and 2016 Democratic nominee Hillary Clinton (right) as candidates who might appease the moderate part of the party if Joe Biden and Pete Buttigieg flame out

'Joe Biden was totally uninspired, right? And I don't think Mayor Pete had that Obama moment he was looking for,' Bannon said referencing South Bend Mayor Pete Buttigieg, the youngest of the Democratic candidates running for president who's seen an uptick in support in the polls.

Bannon said he didn't think the centrist, Wall Street crowd in the Democratic Party would 'sit there and have a coronation for Elizabeth Warren.'

'Yeah, so I think that Bloomberg and Clinton are still there,' Bannon said.

Both Michael Bloomberg, the Republican-turned-Democratic ex-New York City mayor, and Hillary Clinton, the Democrats' 2016 nominee, have said they're not running for president - though aides to Clinton have floated that she hasn't shut the door yet.

'I don't believe that they want to seem like they're disruptors, right, so they don't wan to elbow Biden aside, but as the natural gravity falls out in the first two races - South Carolina is what's propping him up right now,' Bannon explained. 'And Mayor Pete, if Mayor Pete does not get the traction and he did not have an Obama moment the other day, I think the centrists are going to have a vote and they're going to look and say Bloomberg or Clinton are the best shot they have.'

But best doesn't mean the Democrats will win, Bannon also said.

'No, no. The only person who can beat Donald Trump is Donald Trump,' Bannon told Bartiromo. 'There's not a candidate out there who can beat Donald Trump.'