Scott Walker and Jeb Bush are grabbing a lot of attention as they compete with one another to prove who would be more effective in unraveling Obama’s Iran deal. So it’s hardly surprising that Marco Rubio is trying to grab his own piece of the let’s-fulminate-against-Obama’s-capitulation-to-Iran action:

“Senate Democrats face a stark choice when this deal comes before Congress for a vote in September,” the Florida Republican said. “They can either stand with President Obama and allow this flawed ‎agreement to go through, or they can stand with a majority of the American people, our friend Israel and our moderate Arab allies in the region.”…

“This is not America’s deal with Iran. It is Barack Obama’s deal with Iran, and it does not have congressional support,” he said. “It is the duty of Congress to protect American security, not follow what President Obama has described as the ‘broad international consensus.’”

Rubio’s suggestion that a “majority of the American people” opposes the Iran deal is interesting; this week’s Washington Post/ABC News poll shows that 56 percent of them support the deal. Rubio is right in the sense that a majority of Congress almost certainly does not support the agreement — Congress could fail to block it even as majorities in both chambers vote against it. But if anything, that just means Congress is probably to the right of the American people on it.

Rubio’s suggestion that Congress should sink “Obama’s deal,” rather than follow what the president has called the “broad international consensus,” is also an unwitting reminder that the GOP nominee, in vowing to undo the agreement, could find himself in a tougher-than-expected position in the general election. He’ll have to explain to the broader electorate how he’d manage all of the unpleasant international consequences that would flow from doing that, a point Hillary Clinton is likely to draw out. The ongoing battle between Jeb and Walker illustrates how hard that might be to do; thus far, only Jeb has seriously engaged with the idea that it might be a difficult task.

Which raises a question: If the GOP presidential candidates were not locked into a place where they must oppose “Barack Obama’s deal with Iran,” as Rubio put it, mightn’t that leave the GOP nominee with a better argument to make about it in the general election than simply vowing to undo it as quickly as possible?

What if the GOP nominee were to say he has grave concerns about the Iran agreement, yet it just might succeed in preventing Iran from getting a nuke — but only if it were implemented with the sort of toughness and vigilance on national security that a Republican president would bring to the task?

I know that’s a far-fetched notion. But I ran it by a political strategist who held a senior position in both of George W. Bush’s successful presidential campaigns — Matthew Dowd — and he endorsed the idea.

“If I were advising a presidential candidate, I’d tell him to argue that now that we have an agreement in place, it’s better to elect the person who’d be toughest on Iran,” Dowd said. “A Republican is going to be much tougher on Iran than Hillary or any other Democrat would be.”

GOP primary voters might balk at anything that stops short of a full blown pledge to roll back Obama’s policies, of course. But Dowd questioned whether GOP candidates have to shape everything around that notion. (Dowd is an independent but was also a longtime RNC official, in addition to working on Bush’s two campaigns; his views will probably be dismissed as RINO-ism, anyway.)

“It’s only a perception problem that you have to oppose Obama, not a reality problem,” Dowd said. “The current policies haven’t worked with Iran — they’ve proceeded on their path, anyway. I don’t know when it became the Republican position to accept long term policies that are not working. I thought Republicans were the ones who said, ‘let’s try something else,’ just like they do with other failed government programs.”

Interestingly, this week’s Post poll hints that this approach might work. It shows that Americans support the deal by 56-37, but it also shows that more than six in 10 are not confident that it will stop Iran from getting a nuclear weapon. This suggests the American mainstream wants to try engagement but is worried about keeping Iran from cheating on the deal. Clinton’s quotes about the agreement, in fact, seem shaped around this reading of public opinion.

“The American people want the deal and they want someone who is tough enough as president to make Iran honor it,” continues Dowd. “That’s what the Republicans could be arguing. But for some reason they won’t.”