She said her concerns of the party "becoming the Brexit party" had come to pass. Johnson's latest ultimatum makes it clear to MPs on all sides of the House of Commons that he would not, under any circumstances, entertain the notion of another delay to Brexit.
On the prime minister's threat of holding a snap general election, she said: "I don't believe the Conservative party will offer people a sensible choice at the next election in respect of the fact Boris Johnson is going to offer people a general election that offers the no deal or Jeremy Corbyn".
Tory MPs have been warned if they go against the government they'll face deselection, and this morning it was revealed that Greg Clark could be among the casualties.
There has been significant confusion in the past 24 hours about whether Labour would vote in favour of a general election, even if triggered by the prime minister, or whether it is prioritising no-deal legislation.
Mr Johnson appeared to falter as he delivered the statement in which he said MPs publicly opposed to a no-deal would "chop the legs out" from under the United Kingdom negotiating position if they voted to block a no-deal.
Follow all the twists and turns in our live blog later this morning with our political editor Paul Francis.
Nick Boles, a former Conservative who now sits as an independent member of parliament, said the rebels would seek to force the government to ask the European Union for a Brexit delay if it was unable to ratify a revised Withdrawal Agreement by a certain date in October.
I don't want an election, says Boris Johnson in latest Brexit warning
A snap election is simply when a general election is called earlier than expected.
Opposition MPs and rebel members of his Conservative party are planning to vote for delaying beyond October 31 if he can not agree exit terms with Brussels. "We're leaving the 31st of October, no ifs or buts".
Under the Fixed-term Parliaments Act a two-thirds majority is required for an early election and critics have claimed Mr Johnson could seek to simply delay the date of the poll until after Brexit.
The bloc is adamant it will not renegotiate the agreement struck with former Prime Minister Theresa May, which Johnson considers unacceptable.
Former prime minister Theresa May agreed exit terms with Brussels previous year but the deal, which covered Britain's financial contributions, the rights of European Union expatriates and the Irish border, was rejected by parliament thrice.
"Currencies, as a rule, do not like uncertainty.The idea is that there could of course be a no-deal Brexit, which investors do not like.They do not like the idea of the uncertainty or the potential chaos that that could bring", said Jane Foley, of Rabobank on BBC's Radio 4 Today programme.
On Tuesday, Jeremy Corbyn will meet with a group of opposition party leaders in his office, including Ian Blackford from the SNP and Jo Swinson from the Lib Dems, for a further talks on how they might block no deal.
The Prime Minister's official spokesman confirmed that if there was to be an election it would be held before the European Council summit of EU leaders on October 17.