But he warned British lawmakers that they must not expect any substantial or fundamental changes to the withdrawal agreement May signed in Brussels in November.
“Everything has been done in recent weeks and months to signal our interest in a positive decision,” Maas said, as British MPs prepared to vote on the agreement.
“However, I am sceptical that the agreement can be fundamentally reopened once again,” he said.
As things stand, May is likely to lose Tuesday's vote, but more of her Conservative members could get on board if the other 27 EU leaders agree to modify the agreement.
In particular, they want the right to unilaterally end a measure to keep Northern Ireland in the EU customs union until a new trade relationship is agreed.
So far, EU leaders have said changing the deal is impossible – and Maas did not stray far from this line – but any hint of movement will be seized on in London.
“If there were still a solution that could be presented under even greater pressure, I would ask myself why it has not been put on the table before in order to ensure that this evening's vote takes place under better circumstances,” Maas argued.
“That is why I believe that the agreement is as it stands and will not be substantially changed, but that, if things go wrong tonight, there will certainly be talks again.
“But I don't believe that completely new solutions will be put on the table than those that have been negotiated so far,” he warned.