There we go again, Republicans.

We keep shooting ourselves in the feet — and at the worst possible times.

Things were going pretty well for the GOP until Monday.

President Obama was getting major grief from Republicans (and even some Democrats) for preparing to sign America on to a horrible nuclear arms deal with the Iranians.

Hillary Clinton was ensnared in an email-deleting scandal of her own making that was so obviously unlawful and politically devious that even the liberal media were attacking her.

So what did 47 Republican senators do?

They attracted the full attention of the mainstream media by sending a letter to the Iranian ayatollahs reminding them that any agreement the president signs without approval of the Senate can be undone by the next president faster than you can spell Bibi Netanyahu.

Nice job, Republicans.

Yes, what you told the Iranians in the letter was right. Any B-plus middle-school civics student knows that the Senate gets to ratify or reject treaties made by the president.

But sending an open letter to Iran was dead wrong — and politically stupid.

It merely gave Democrats — and their media buddies — a chance to change the subject and accuse Republicans of irresponsibly trying to sabotage the president’s foreign policy.

What rookie Sen. Tom Cotton of Arkansas and his co-signers did with their letter was nothing new.

Members of Congress have been trying to score political points by undercutting the president’s treaty-making power for decades.

Ted Kennedy did it in the late 1970s when he tried to get the Soviets to do something to embarrass Jimmy Carter so he could take the nomination from Carter in 1980.

Kennedy pulled the same slimy trick against Ronald Reagan in 1983, when he sent emissaries to Moscow and offered to obstruct my father’s anti-Soviet foreign policy in Congress if the Kremlin helped Teddy run for president in 1984.

In 1987 Democrat House Speaker Jim Wright stuck his congressional nose into the negotiations between the Reagan administration and the Sandinistas in Nicaragua.

More recently, who can forget Nancy Pelosi’s jaunt to Syria in 2007, when she and a gang of House Democrats made nice with Bashar al-Assad at the same time the Bush administration was trying to put pressure on Syria to work with it on Mideast peace talks?

Those 47 Republican senators didn’t need to send a public letter to Teheran to remind the Iranians how America’s separation of powers works.

What was wrong with Sen. Cotton and a few others writing an op-ed piece about the Senate’s treaty-ratifying powers for the Wall Street Journal?

I bet the Iranians would have gotten the message just as well.

Instead Republicans only brought attention — bad attention — on themselves for doing exactly what many of them had rightly criticized Pelosi for doing.

Republicans in the Senate should have shut up and let Obama negotiate and sign the treaty with Iran, bad as it is bound to be.

Then they could have pointed out to the Iranians and everyone else that the deal needed to be ratified by two-thirds of the U.S. Senate – and that 47 Republicans were strongly against it.

The letter was a blunder. Until the senators sent it, Iran was exclusively Obama’s problem.

All the media attention was on the president’s defense of his treaty and Netanyahu’s concerns about how dangerous and naive it was.

Republicans should be sitting pretty right now and the media should be focusing on Obama’s and Hillary’s problems.

But now the Iran nuke deal is not just Obama’s issue. It’s the Republicans’ too.

And if anything goes wrong, which it probably will, you can bet that Republicans will – as usual – get most of the blame.

Copyright ©2015 Michael Reagan