Trump could have asked Ryan and McConnell for a funding commitment in November of 2016. Had it not been forthcoming, he should have declared an emergency then, when the republicans had a majority in both houses.
He may yet build, if he can avoid a veto override, but you can’t relieve him of responsibility. He made the promise a hundred times and he will sink or swim on that basis.
Trump should be judged by the only that matters, results.
With only a minor reduction in refugee numbers, no reduction in legal immigration (and promised INCREASES), and a massive surge in illegal immigration - the results are very poor.