Obama's tough task: Selling Iran nuke deal to Congress

President Obama will begin the tough work of selling the administration's framework agreement with Iran to skeptical politicians at home, reports CBS News correspondent Major Garrett.

The White House will begin briefing key leaders on classified and unclassified details next week. The imperative is to keep Congress from passing new sanctions or demanding congressional approval of the accord. On both, veto fights could be on the horizon, because skepticism is bipartisan.

Mr. Obama warned Congress that meddling with the emerging nuclear deal with Iran could bring the U.S. closer to war.

"If Congress kills this deal, then it's the United States that will be blamed for the failure of diplomacy," he said. "International unity will collapse, and the path to conflict will widen."

In an interview with CBS News correspondent Margaret Brennan, Secretary of State John Kerry repeated calls for members of Congress not to impose new sanctions.

"New sanctions now would clearly be unnecessary, given what we've been able to achieve and yes, it would have a profoundly negative impact on this," Kerry said. "It would be highly irresponsible to simply break this apart by now stepping in the middle when the measure of this agreement, I believe, can stand the test of scrutiny."

Mr. Obama telephoned top Republican and Democratic leaders to outline the deal. Many lawmakers reacted cautiously, insisting on more details.

Sen. Charles Schumer (D-New York), typically a strong White House ally, said nothing positive, saying only the deal "deserves careful, rigorous and deliberate analysis," adding he will give it "a very careful look."

Freshman Sen. Tom Cotton (R-Arkansas) has seen enough.

"The terms announced today are not as bad as I had feared, they're much worse. They put Iran on the path to a nuclear weapon whether Iran follows those terms or whether Iran breaks those terms," he said. "The only blame that's deserved is President Obama for starting down this dangerous path and now continuing down it."

The president insists Iran would be forced under terms of the deal to open up its nuclear program to international inspections and denied any pathway to a nuclear weapon. To keep Congress in check, the White House will need more Democratic allies than it has now.

"I think there's some important work for the administration to do to persuade Democrats that this is a framework that they should support; there's a lot of work that's not been done," Sen. Chris Coons (D-Delaware) said.

Top officials describe initial congressional reaction as encouraging. They feared more opposition than has registered so far.

But Coons told CBS News the White House would be wise not to underestimate congressional skepticism and the political damage it could do to what Mr. Obama regards as a signature diplomatic accomplishment.