LONDON — Prime Minister Boris Johnson and Labour leader Jeremy Corbyn went head-to-head Tuesday night in the first televised debate ahead of the U.K.'s December 12 election.

The two leaders locked horns over Brexit and stuck closely to their top campaign messages in the first set-piece clash of the election, although they also engaged in an argument over Corbyn’s claim that U.S. health companies will have access to the U.K.’s National Health Service in a post-Brexit trade deal.

A snap poll by YouGov revealed the two leaders were almost neck-and-neck in the eyes of the public, with 51 percent of respondants saying Johnson won the debate and 49 percent calling Corbyn the winner.

The result will be a moderate boost for Corbyn, who went into the debate trailing Johnson in the polls, but will not give the Labour leader the kind of game-changing moment he needs to radically change the campaign.

Here are six takeaways from the ITV debate:

1. Brexit ain't over

Johnson stressed his commitment to leaving the EU by January 31, 2020, after the leaders were asked whether they could reassure the public that Brexit will not drag on forever.

“If you vote for us, we have a deal that is ready to go. Approved by every one of the 635 Conservatives candidates standing at this election,” he said. “As soon as we can get that deal through parliament, as we can in the next few weeks, we can get on with the people’s priorities.”

Corbyn described Johnson’s commitment as “nonsense” and said negotiations for a trade deal with the U.S. as Johnson wants would take at least seven years while at the same time he'd hold talks with the EU on trade, claiming: “The two things are actually incompatible.”

If the U.K. leaves the EU on January 31, it will have 11 months to negotiate a trade deal with the EU before the end of the transition period in December 2020, as set out in the deal Johnson struck with the EU in October. This deadline could be extended to allow for more negotiating time. The EU took seven years to negotiate and ratify its trade deal with Canada.

2. Corbyn can’t give a straight answer on Brexit

Labour’s position on Brexit is that it would renegotiate a new deal with the EU and put it to a referendum within six months. But Corbyn refused repeatedly to reveal which way he would campaign in this second referendum, saying simply that he wanted to “bring people together.” Johnson seized the opportunity to attack Corbyn repeatedly on his failure to give a straight answer.

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The Labour leader would not even put the issue to bed by suggesting that he would stay neutral, decide depending on what he could negotiate with Brussels, or follow whatever decision Labour members take. He drew laughter from the audience when he claimed to have made his position clear.

Corbyn’s equivocality on a question that most Brits consider one of the biggest issues facing the country has the potential to hurt him severely at this election. Labour’s fate will depend on whether Remainers in key battleground seats hold their noses and vote for the party anyway.

3. 'Appalling level of lies'

Johnson drew laughter from the audience at the ITV studio by saying he thought the “truth matters.”

Julie Etchingham, who chaired the debate, pressed the prime minister on the importance of personal integrity and individual character in the election, Johnson pivoted back to Brexit. “I think it does, and I think it very important to hear from, I’ve been very clear about the [Brexit] deal that I’ve done — there it is, it’s in black and white,” he said.

The public’s growing weariness with the quality of political debate in the U.K. was evident when a questioner said the atmosphere had become toxic with an “appalling level of lies.”

The two leaders agreed to improve the quality of political debate and shook hands, with Corbyn conceding that debates in parliament just before its dissolution were “vicious and horrible.”

During the debate, the Conservative Party press office came under sustained criticism for renaming their Twitter account "FactCheckUK."

4. Corbyn leaves open second Scottish referendum

Johnson accused Corbyn of planning to strike a deal with the Scottish National Party to form a “chaotic coalition” that would call a second referendum on the independence of Scotland.

Corbyn replied saying the prime minister's suggestions were “nonsense.” The Labour leader said: “There’s not going to be a coalition between Labour and anybody else. There are no deals that have been done and there will be no deals that are done."

Asked to rule out a second Scottish independence referendum before the end of the first year of a Labour government, Corbyn said: “I’ve said there would be no deal with the SNP, there would be no support for a Scottish referendum in the early years of the next Labour government, because I want to invest in Scotland and give Scotland the £70 billion it needs in capital investment.”

Johnson challenged Corbyn, saying he had not clearly ruled out a second Scottish referendum. “I listened very carefully as I always do to Mr Corbyn — I didn’t hear him say he was going to rule out a referendum on Scotland. Did you?”

5. Health battleground

Both parties are aware of the crucial importance of health policy at this election. Corbyn seized on the public’s propensity to trust Labour more on the NHS, accusing Johnson of selling out to U.S. pharma companies.

Corbyn said Johnson had been conducting “secret meetings” with U.S. officials about the NHS and a future trade deal. He said the government was “proposing to open up our NHS markets, as they call them, to American companies.”

Johnson said this was “completely untrue” and an “absolute invention” that was being peddled by Corbyn. “There are no circumstances whatever in which this government or any Conservative government will put the NHS on the table in any trade negotiation.”

Corbyn scored a political victory, saying the monarchy "needs some improvement" and began one answer with “we should discuss the victims.”

“We will continue to fund the NHS massively as we are,” Johnson said “and we can only do so if we have a strong and dynamic economy.” The Tories are trying to shift the health debate towards safer ground: their reputation for good management of the country’s finances.

But Corbyn pointed out that emergency waiting times are at their longest ever, and said Johnson’s claim that he has committed to building 40 new hospitals is untrue. Last month the government promised new money to upgrade six hospitals. Up to 38 other hospitals have received money to plan future building work between 2025 and 2030 but not to begin building.

6. Royal disruption

Corbyn and Johnson were asked about Prince Andrew, who has dominated headlines since Saturday when he defended his friendship with American billionaire Jeffrey Epstein, who was convicted of sex offenses, and denied having sex with a trafficked minor. Epstein was found dead in his prison cell in August in an apparent suicide.

The prime minister looked deeply uncomfortable with the question and said that “the institution of the monarchy is beyond reproach.” Corbyn, however, scored a political victory, saying the monarchy "needs some improvement" and began one answer with “we should discuss the victims.”

The scandal has captured the British public’s attention far more than anything else during this pre-election period and the fallout has potential to disrupt the campaign.