(Bloomberg) — At least a few of the U.S. Republican
senators feeling the backlash from signing an open letter to
Iran’s leaders are expressing some second thoughts.

Amid mounting criticism from allies, home-state editorial
boards and colleagues who opted not to sign the missive, Senator
Ron Johnson became the latest Republican to suggest he might do
things differently if given another chance.

While Johnson said he stood by the content of the letter,
which warned Iran that any deal they get from President Barack
Obama might not outlast his term in office, he said it probably
shouldn’t have been directed to leaders of the Islamic Republic.

‘I suppose the only regret is who it’s addressed to,’’
Johnson said at a Bloomberg breakfast in Washington. The
Wisconsin Republican said it may have been a “tactical error”
and that the letter could have been addressed to Obama’s
administration or the American people.

Arizona Senator John McCain, a prominent Republican voice
on foreign affairs and national security, has said that haste
and an impending snowstorm in Washington short-circuited more
measured consideration of the letter.

“It was kind of a very rapid process. Everybody was
looking forward to getting out of town because of the
snowstorm,” McCain told Politico in an interview. “I think we
probably should have had more discussion about it, given the
blowback that there is.”

Administration Pushback

The White House, which was facing pushback on the Iran
nuclear negotiations from some Democrats as well as Republicans,
seized on the letter to argue that Republicans were making
foreign policy a partisan issue. Obama and his aides have
responded with a mix of scolding and disdain.

The president told reporters at the White House on Monday
that the lawmakers seemed to be “wanting to make common cause
with the hardliners in Iran.” In a recorded interview with the
website Vice, an excerpt of which was released Friday, Obama
said, “I’m embarrassed for them.”

European allies who also are party to the Iran negotiations
have condemned the letter as counterproductive.

“Suddenly, Iran can say to us: ‘Are your proposals
actually trustworthy if 47 senators say that no matter what the
government agrees to, we can subsequently take it off the
table?’ ” German Foreign Minister Frank-Walter Steinmeier said
Thursday during remarks at the Center for Strategic and
International Studies in Washington.

Not Politics

“This is no small matter we’re talking about,” Steinmeier
said. “This is not just an issue of American domestic
politics.”

The letter has shifted attention away from Israeli Prime
Minister Benjamin Netanyahu’s speech earlier this month to a
joint meeting of Congress. His presence, at the invitation of
House Speaker John Boehner, and remarks had forced the White
House to defend the framework of a nuclear deal.

Senate Foreign Relations Chairman Bob Corker of Tennessee,
who didn’t sign the letter and is shepherding legislation that
would require congressional approval for any nuclear deal with
Iran, said it wasn’t helpful to his efforts to round up
Democratic votes for the measure.

The letter was signed by 47 of the 54 Republican senators,
including four who are considering bids for the party’s 2016
presidential nomination.

One of the candidates, Kentucky Senator Rand Paul, said on
NBC’s “Today Show” on Wednesday that the letter was intended
to “strengthen the president’s hand” in negotiations.

Letter’s Content

No Republican has stepped back from the content of the
letter, which warned Iran that any agreement they struck with
Obama to curb its nuclear program may be reversed by his
successor or changed by U.S. lawmakers. McCain told reporters he
was “glad” to have signed it.

South Carolina Republican Senator Lindsey Graham said he
doesn’t have any second thoughts about sending the letter.

“At the end of the day, I want the ayatollah to understand
that our president doesn’t have the ability on his own to waive
congressional sanctions without our input and he is claiming he
has that right,” Graham said on Fox News. “This is a
constitutional crisis in the making. No Senate or House should
ever let any president do away with congressional sanctions
created by the bodies without their approval.”

To contact the reporter on this story:
Justin Sink in Washington at
jsink1@bloomberg.net

To contact the editors responsible for this story:
Joe Sobczyk at
jsobczyk@bloomberg.net
Bernard Kohn