The government has defended the UK’s Brexit deal with the EU, following criticism from the US president.
Donald Trump said the US “can’t make a trade deal with the UK” under Boris Johnson’s EU withdrawal agreement.
But Housing Secretary Robert Jenrick said the PM’s plan was a “good deal” that allows the UK to “strike free trade deals around the world”.
Other comments made by Mr Trump led Labour to accuse him of trying to “interfere” in the election.
Speaking to LBC, the president said Mr Corbyn would be “so bad” as prime minister and that Mr Johnson was “the exact right guy for the times”.
Mr Corbyn accused him of “trying to interfere” in the UK general election to boost “his friend Boris Johnson”.
The UK is going to the polls on 12 December following a further delay to the UK’s departure from the EU, to 31 January 2020.
Mr Johnson hopes to win a majority of seats so that he can get his deal through Parliament – while Mr Corbyn promises another referendum if he wins the keys to 10 Downing Street.
But Mr Trump said his longstanding ally Mr Farage – leader of the Brexit Party – should team up with Boris Johnson to do “something terrific”, saying they would be “an unstoppable force” in the December poll.
Mr Farage’s party is due to hold its campaign launch later amid speculation about whether they will field MPs in every seat or stand down candidates to help Tory Brexiteers win.
Speaking on LBC this morning, Mr Farage said his view was there needed to be “some kind of alliance” – but he would not comment on whether the Brexit Party would be fielding “20 or 200 candidates”.
In August, Mr Trump promised a “very big trade deal” with the UK and predicted that leaving the EU would be like losing “an anchor round the ankle”.
But speaking to supporter Nigel Farage on LBC, Mr Trump was critical of the withdrawal agreement Mr Johnson recently reached with EU leaders.
Mr Trump said: “We want to do trade with UK and they want to do trade with us.”
But he added: “To be honest with you… this deal… under certain aspects of the [Brexit] deal… you can’t do it, you can’t trade.
“We can’t make a trade deal with the UK because I think we can do many times the numbers that we’re doing right now and certainly much bigger numbers than you are doing under the European Union.”
Mr Trump, who has previously expressed his backing for Brexit, did not elaborate on what difficulties he thought might arise in striking a US-UK trade deal.
In response, a Downing Street spokesperson said Mr Johnson’s Brexit deal with the EU “ensures that we take back control of our laws, trade, borders and money”.
Asked if the president’s assessment was wrong, Mr Jenrick told BBC Radio 4’s Today programme: “We know the deal enables us to secure deals with a range of growing economies [and] we’ll be setting out to do that.”
He also claimed initial conversations with the US about a trade deal had been “positive”.
Not part of Johnson’s election plan
Analysis by Jonathan Blake, BBC political correspondent
Downing Street was very quick to put out a statement on Thursday night defending Boris Johnson’s deal.
But there is no doubt it is a blow to have the president of the United States suggesting the deal the PM has negotiated with the EU will somehow hamper and limit the UK’s ability to do a free trade deal with the US in future.
It strikes at the heart of the Conservatives’ key message for the election campaign to come.
And there will be frustration, if not stronger feelings, within Downing Street about the president’s comments.
One consolation for them is the president going out of his way to say the US has no intention of interfering in the NHS as part of any trade deal.
But there is no doubt this was certainly not part of the plan or helpful for Boris Johnson at this point.
Mr Corbyn has said a post-Brexit trade deal with Mr Trump’s administration would give US companies greater access to the NHS, and allow them to profit from it at UK taxpayers’ expense.
Shadow international trade secretary Barry Gardiner told Today the NHS was “clearly in the negotiating mandate” and “it is clearly something which [Mr Trump] in the past has said is absolutely on the table”.
However, the president dismissed the Labour leader’s claim, saying: “Not at all. We wouldn’t even be involved in that, no. It’s not for us to have anything to do with your health care system. No, we’re just talking about trade.”
The UK government has said that, under any future trade deal with the US, it wants protections for the NHS.