Various solutions have been proposed to the Irish backstop issue in the Withdrawal Agreement, but none appear to appease the concerns of those who oppose the Backstop. The Withdrawal Agreement may be rejected by the House of Commons because of the Irish Backstop.
I have to say that I find the idea of regulatory checks on flows of goods within a country (as envisaged in the Backstop) very strange in the 21st century, particularly as most of Northern Ireland’s trade flows are with the UK. I can’t think of a major European country which has had internal regulatory checks on goods since the 19th century of the kind envisaged between the UK and Northern Ireland? The UK has not had such checks since the Act of Union with Scotland in 1707!
The Backstop comes into play if the future trade agreement between the UK and EU is not agreed and the UK does not extend the transition period.
So, at that point the UK has three options, not two.
First, extend the transition period and remain in EU regulation.
Second, move to the backstop. Northern Ireland remains within EU regulation.
Both these options mean a continuation of trade negotiations.
The third option is to end negotiations if they are not proceeding successfully or speedily and not extend the transition agreement or implement the Backstop. This would mean the Withdrawal Agreement falls away as the UK can unilaterally end the Agreement but not the Backstop within the Agreement.
It would be possible to give the UK parliament a vote on what to do at the end of the transition period at the end of 2020. This would mean Parliament would have to decide to choose at that date between extending the transition period, implementing the backstop or withdrawing from the Withdrawal Agreement.