"It's hard to conceive of that happening," Schapiro said. "I really don't see a scenario under which he can be beaten."
Five months later, Schapiro, whose Atlanta-based firm also does campaign polling, hasn't changed her mind.
"I still don't see how he gets knocked off," she said last week.
Her assessment of the freshman Republican's prospects is widespread in Georgia political circles.
And apparently with good reason.
A recent Strategic Vision poll suggests Isakson likely is the most popular statewide political figure in Georgia.
He had a 54 percent job approval rating, compared to 51 percent for Gov. Sonny Perdue and 48 percent for U.S. Sen. Saxby Chambliss.
Forget, at least for now, about a Democrat getting help from Barack Obama next year. Forget that, although he eventually lost to Chambliss, U.S. Senate candidate Jim Martin got a boost from Obama last year.
Obama's approval rating in the recent poll was just 40 percent - down from 55 percent in April. So it might be just as well for Democrats that he won't be on the ballot next year.
Moreover, Isakson's re-election campaign is up and running and recently reported that it had more than $3 million in the bank.
In contrast, Democrats won't know who their nominee will be until after next July's primary. So far, there aren't even any announced wannabes. And University of Georgia political scientist Charles Bullock notes that mid-term elections rarely favor the party in control of the White House.
"While 1998 and 2002 were notable exceptions," Bullock said, "2006 followed the pattern and 2010 is likely to."
Bullock and others also observe that, due to retirements, several GOP Senate seats will be open next year.
"Democrats," he said, "will concentrate on winning those and largely ignore a Republican who looks as safe as Isakson."
David Johnson, CEO of Strategic Vision, agrees, saying Democrats will focus on Senate races in states such as Missouri, Nevada and Ohio.
Last year, Democrats had a lot going for them.
But even the unpopularity of George W. Bush and Obama's dynamic appeal weren't enough for them to win in Georgia.
Without Bush to kick around and slim prospects for any boost from Obama, Georgia Democrats likely will target the governor's race next year.
That may be their best prospect; after all, the closest thing to an incumbent in that race is former Democratic Gov. Roy Barnes.
Johnson thinks that the only hazard Isakson faces is being so confident that he strays too far from the GOP's conservative base.
If he does, Johnson said, right-leaning voters might support the Libertarian candidate, as some did last year.
That could make a difference in a close race, although few observers now expect it to be close.
Here's why: Georgia remains a red state; no non-incumbent Democrat has won statewide since 1998.
Even so, state Democratic Party spokesman Martin Matheny says it's too early to rule out an upset because the general election is 15 months away.
Isakson's voting record, Matheny reasons, can be used against him.
In hewing to the Republican party line, Matheny said, Isakson "opposed everything and didn't come up with anything positive of his own."
But Schapiro, among others, questions whether that will sway most voters.
"I think he does a good job of working on behalf of what he believes to be the majority of Georgians and of serving his constituents," she said.
"Basically, Democrats are asking people to fire him. I just don't see any ground swell of support for that."