...Why aren't the Republicans standing with the US?...
But they
ARE standing with the US.
Against a President who appears to be acting in a weak and naive manner, in dealing with a barbaric Iranian theocracy, against the interests of the United States.
They
ARE standing with the US.
There are merely standing AGAINST its present Lame-Duck executive, who has lost the trust of much of Congress, and much of the American People, and who has repeatedly demonstrated that he now needs to be kept on a short Congressional Leash, to minimize the damage he does between now and January 20, 2017.
The
President is not the US.
You and I are the US.
The Pubs are doing a great job of manifesting as
Standing With the People and the Republic, rather than its present autocrat, who rules by Imperial Decree.
Standing against the President is
not ipso facto the same thing as standing against the Nation.
It's simply that it has been so long since there has been such division between the President and the Congress and the People, that this old state of affairs seems new again - we've forgotten that Congress was designed to act as a Braking Mechanism on a runaway or misguided Executive, which is exactly what we see unfolding in the present day.
The Constitution is working exactly as the Founding Fathers intended in this context, and the Universe is unfolding as it should. All is well, in that regard.
...Why did they promise Iran they could build their nukes?...
The Republicans did not promise Iran that they could build nuclear weapons.
They merely told the Iranians that Congress would not honor any Bad Deal made by this current and un-trusted President.
Putting them on notice that they would face a much harsher scrutiny and/or bargaining and/or sanctions and/or worse, once we get past January 20, 2017.
...Why did they purposely sabotage their own country?...
They did not.
They acted within their Constitutional Mandate, to prevent a misguided and un-trusted President from sabotaging his own country's interests.
...And why are so many RW's eager to do the same?
Indeed.
A great many Americans on the Right and in the Center, are eager to prevent a misguided and un-trusted President, from sabotaging his own country's interests.
Although, unlike you few remaining Orgasmic ObamaBots, who accuse your Opponents of 'purposely sabotaging', your Opponents, upon reflection, will, for the most part, not attribute 'purposeful sabotage' to you-and-yours, but rainbows and unicorns and naivete and foolhardy self-delusion as the basis and motivation for your own pathetic outcomes.
Hope that helps to clear things up a bit.