Amber Rudd, a senior Member of Parliament (MP), has quit her job in the government saying not enough is being done to get a good Brexit deal.
She has also left the Conservative Party along with her role as the work and pensions secretary.
She was a key member of Prime Minister Boris Johnson's cabinet but has spoken out against his leadership.
She told the BBC there were currently no "formal negotiations" taking place with the EU, just "conversations".
It's been a hugely important week in Parliament with plenty of people scratching their heads as to what happens next with Brexit?
Earlier this week, MPs backed a bill which aims to stop no-deal Brexit from happening but Mr Johnson says he wants the UK to leave the EU on 31 October, whether or not a deal has been agreed.
During Wednesday evening's crucial vote, MPs who disagree with Mr Johnson's Brexit plans came one step closer to forcing him to go back to the EU to ask for an extension to the Brexit deadline, if there's no progress by 19 October.
There was also argument about whether or not - or rather when - there should be a general election, but another vote was held about this - and MPs rejected the idea.
It doesn't mean that an election can't happen at some point - it still could, although we don't know anything for certain - but we do know that it won't be happening right now.