In a televised conference on Monday, Brexit party leader Nigel Farage said his party will not field any candidates in 317 constituencies held by ruling Conservatives focusing instead in Labour-held constituencies.

That is what Farage calls a “unilateral” Leave alliance.

Prime Minister Boris Johnson hailed Farage’s decision, claiming it would help to avoid another hung Parliament. Markets also responded positively to Farage’s pledge.

The Brexit Party leader had previously threatened to field 600 candidates across the country unless the Conservatives abandoned the Withdrawal Agreement concluded between the European Commission and Johnson. Now, Farage is changing strategy and will only field candidates in seats the Conservatives do not already hold.

The Conservatives are hoping to seize traditional Labour seats in northern England, uniting the Leave vote. But analysts are split as to whether Farage poses a bigger threat to the Conservatives or to Labour.

Farage claims that traditional working-class voters who voted Leave are more likely to support the Brexit party than stand behind the toxic Tory brand. Tory chairman James Cleverly said on Monday that the danger remains that the Brexit Party will split the Leave vote in the North of England, depriving the Conservatives of a victory and, thereby, “frustrate the Brexit process”.

Farage justified his conciliatory move by suggesting he is meeting Johnson halfway. On Sunday evening, Johnson vowed not to extend the post-Brexit transition period beyond the end of 2020 and to negotiate “a straight” trade deal, like Canada, with no normative alignment. “This sounds more like Brexit,” Farage said.

“This is a Nigel Farage and Boris Johnson alliance with Donald Trump to sell out our country and send £500 million per week from our NHS to US drugs companies,” Labour Party Chairman Ian Lavery said on Monday. He was referring to a trade deal with the US that may entail US pharmaceuticals imposing higher prices on Britain’s NHS.

Liberal Democrat deputy leader Sir Ed Davey said Mr Farage’s decision “shows the Conservatives and the Brexit Party are now one and the same”.

Scottish National Party leader Nicola Sturgeon said the Conservatives have “effectively become the Brexit Party”.

Anti-Brexit parties Plaid Cymru, the Green Party and the Liberal Democrats have made a comparable pact not to run against each other in 60 seats across England and Wales.