Claims second Trump impeachment isn't constitutional are non-sense.

I'm not American. And while I understand that this is unprecedented and that the constitution may not be crystal clear on this matter it is actually QUITE easy to make the case that the constitution did intend for this situation to be possible.

The fact that the impeachment process exists at all and that we have seen during Trump's time in office that it is effectively impossible to prosecute a sitting President under any other mechanism is all the proof you need.

If Republicans were to win on a vote that it would be unconstitutional then they are creating a gap. They would making it possible for a sitting President to act in any way they choose and violate and Federal laws they like, without fear of prosecution during the closing days of their Presidency.

And, there is no sane person who would interpret the constitution as such. Because, as stated, this is why impeachment exists in the first place.

In fact, I think that the impeachment process needs to be viewed in the light that the only requirement be that the actions under consideration for impeachment happened during the President's time in office. It shouldn't even be necessary for a vote on impeachment or anything else to occur.

Why? Simply put, facts might not surface until after the President has left office.

Furthermore, I don't think that the argument about the presence of the Chief Justice being present holds water either. I can understand the necessity of having the highest ranking judge preside over the trial if the accused is still acting in their capacity as the President. But, the same sensitivity isn't required if the trial held after the person has left office. Nor is the role much other than a symbolic one. 

Basically, I think the only real avenue the Republicans have would be not to decide on the constitutionality of this act, but rather to determine who has the authority to try this case. It MUST be possible to take it to trial. And the outcome MUST be enforceable. Otherwise, the door is left open for criminality. Frankly, if I were a Democrat, I might be willing to take up this vote if the House and Senate were willing to come to an agreement that, if it IS deemed unconstitutional, that it must also then be deemed acceptable to have the matter pursued in other courts.

And, frankly, I don't think that will ever pass muster. The person of the President, while acting in that capacity would have access to classified materials. And so, it is entirely possible that to successfully try such a case that the authorities involved would need access to that information as well. In short, I really can't see a way around it. Crimes must still be paid for, and even if the person in question is a former President, the required evidence will, sooner or later, be sensitive enough that only top elected officials would be able to gain access.

Furthermore, I don't think it would be complicated to compel the Chief Justice to preside over the trial, if for no other reason than to eliminate that potential aspect of the complaints of the processes unconstitutionality.