The Conservatives have opened up a four-point lead over Labour despite Theresa May’s mounting troubles over Brexit, according to the latest Opinium/Observer poll.

The Tories have gained two points since last week and are now at 41%, while Labour has fallen by two points to 37%.

Next week will be a pivotal one for the Brexit negotiations and May’s premiership. May will attend an EU leaders’ summit starting on Wednesday where she hopes to finalise a deal. But several of May’s cabinet ministers and her coalition partners, the Democratic Unionist Party, have warned that there will be consequences if she surrenders too much to the EU.

Despite her party’s boost in the polls, May’s personal approval rating, which rose to -12% last week following her party conference speech, has fallen to -17%. Jeremy Corbyn’s approval rating has stayed the same since last week at -20%.

The Conservatives are the more trusted party to lead the Brexit negotiations according to the poll, with 29% of respondents saying they trusted the Tories more compared to 18% for Labour.

Among leave supporters the figure is even higher, with 41% saying they trust the Tories most to lead the negotiations, up from 32% since May unveiled her Chequers plan in July.

If the government is unable to reach a deal with the EU, 31% of respondents said the UK should leave without a deal and with no further votes, 23% said there should a second Brexit referendum, 14% said there should be a general election and 13% said the government should try to extend the negotiation period beyond March 2019.