During last night's presidential debate, usage maven Bryan A. Garner opined on Twitter that "President Obama is addicted to 'is is.'" Garner also directed Twitter followers to his treatment of "is is" in Garner's Modern American Usage, where he writes, "Rarely is this form found in writing, even when speech containing it is transcribed. In any event, it isn't an expression for careful speakers." But few would characterize Obama (despite his occasional lapses) as a careless speaker, and we do in fact have accurate transcripts of all three presidential debates to test the claim that Obama has an "is is" addiction. So let's check.
In the first debate, one of Obama's "is is" uses was not in fact what Michael Shapiro and Michael C. Haley call "the reduplicative copula" in their 2002 article in American Speech — with a "grammatically superfluous" second is, as Garner puts it. Instead, Obama used the "what X is is" construction (known as a WH-cleft or pseudo-cleft), in which the second "is" is not superfluous:
Wh-when Governor Romney talks about this board, for example
unelected board that we've created
what this is, is a group of health care experts, doctors, et cetera
to figure out how can we
reduce the cost of care in the system overall.
In GMAU, Garner is careful to distinguish the pseudo-cleft "what it is is" from other cases of "is is." Though he does not brand it ungrammatical, he calls it an "ungainly construction" and counsels that "a better method in many contexts is to avoid the what-construction altogether and make the sentence more direct."
Ungainly as the construction might be, we won't count that toward Obama's "is is" tally. In another part of the debate, however, Obama managed to follow a WH-clause ("what has to happen") with a doubled copula, so in that case the second "is" was truly extraneous:
And if you are going to save any money through
what Governor Romney's proposing
uh, what has to happen is, is that
the money has to come from somewhere.
In the second debate, as in the first, Obama used "is is" in the grammatically superfluous manner just once:
Earlier Governor Romney talked about
he wants to make Pell Grants and
uh, other education
uh, accessible for young people.
Well, the truth of the matter is, is that
that's exactly what we've done.
And in the third and final debate last night, Obama did it twice:
Governor, the problem is, is that
on a whole range of issues
whether it's the Middle East
whether it's Afghanistan
whether it's Iraq
whether it's now, uh, Iran
you've been all over the map.
But what the American people understand is, is that
I look at what we need to get done to keep the American people safe
and to move our interests forward
and I make those decisions.
The last case ("what the American people understand is, is that…") resembles the first debate's "what has to happen is, is that…": a WH-clause followed by a doubled copula. For connoisseurs of the "is is" phenomenon, this construction is particularly interesting, because it conceivably allows for the elusive triple "is". A triple "is" could have occurred if Obama's WH-clause had instead ended in "is" (e.g., "What the American people's understanding is, is, is that…").
So unless I've missed something, that's a total of four examples of "is is" in three debates (plus one example of the pseudo-cleft "what this is is"). I don't think that quite qualifies as an addiction — more of a predilection. For a real "is is" addict, see Mark Liberman's post about Kevin Slavin's TED talk, "Xtreme Isisism." (And see links therein for more discussion of the "is is" construction, aka ISIS.)
Update: Looking again at the transcript of last night's debate, I see I missed two other potential cases of "is is," which happened to have occurred in consecutive sentences from Obama:
And so one of the things that we've been doing is, is
for example, organizing entrepreneurship conferences with these Egyptians
to, to give them a sense of how they can start rebuilding their economy
in a way that's noncorrupt, that's transparent.
But what is also important for us to understand is, is that
for America to be successful in this region
there are some things that we're going to have to do here at home as well.
I'm not sure if the first example ("one of the things that we've been doing is, is…") counts, since to my ear it sounds more like a disfluent stammer than the other more clear-cut cases. But the second one does seem to fit the bill, as it occurs in a frame we've seen Obama use previously: a WH-clause followed by a doubled copula ("what is also important for us to understand is, is that…").