Ignore the noise, Theresa May could be the only one who gets Brexit reality.

Theresa May stands firm, defends Brexit draft 04:15

London (CNN)UK Prime Minister Theresa May seems to be the only person in Westminster who understands the Brexit reality: a deal doesn't exist that satisfies everyone in the UK and everyone in Brussels.

She's got a deal, she thinks it's the best deal, and she doesn't seem bothered that very few people agree with her.

Despite hearing MP after MP tell her in the House of Commons on Thursday that they were ready to vote against her proposed deal with Brussels and losing a number of government ministers, the Prime Minister said in a news conference that she is still taking the deal to Parliament.

Some would call it brave; others would call it lunacy. But May is going to face down her most vocal critics in the most public, damning way imaginable.

Briefly, seems to come down to essentially one question: is it more important for the UK to have an independent trading policy or to have a hard border between the Republic of Ireland, which will remain in the EU, and Northern Ireland, which will remain a part of the UK? Everything else -- laws, borders, even money -- hangs on this question being answered.

For the record, it's worth pointing out that a hard border is something the EU and the Republic of Ireland absolutely will not tolerate.

And it's pretty clear now that having both is not possible.

May's deal with the EU, her supporters would tell you, gets as close to both options as is ever going to be possible. Still, it's not enough for large sections of the UK parliament, who will have a say on the deal when May has it signed off in Brussels.

British PM Theresa May strikes Brexit deal with cabinet 01:25

From Scottish nationalists to Northern Irish unionists to countryside Brexiteers, this is a deal that doesn't address their foremost concerns. These concerns vary from shaking the shackles of EU law and regulation to maintaining access to the EU's single market. Some even want to chuck the whole thing and rejoin the EU.

So why on earth would the Prime Minister take the vote to the Commons knowing there's a real chance she could lose? Why is she not changing course and going back to Brussels to try for more concessions?

May has a habit of hanging on and proving us all wrong. Ever since she lost her majority in Parliament in last year's election, her leadership has been in constant question. But on she goes.

It could be brinksmanship. It could be confidence. It could even be a direct challenge to her own party: back me or push me.

Brexit basics: Key points from the draft deal

All day, we have heard rumors of her MPs submitting letters of no confidence in her leadership, a process that could lead to a vote that could dislodge her as Prime Minister.

Or not. There is still the very real possibility that she could win such a vote and strengthen her position among her own MPs. But even at that point, the arithmetic of Parliament would remain something of a mystery.

And it's a mystery that needs solving very soon. Businesses, investors, employers and diplomatic allies want clarity.

And until that mystery is solved, the real costs will stack up. The pound will continue to be volatile, jobs will continue to be put at risk and economists will continue to tear their hair out.

But this isn't about economics; it's about the mayhem in a country whose politics have barely functioned in 2018.