This hasn't troubled many of his voters, who already largely believe that this could or will happen.
The good news for Trump and those concerned about voter fraud: There are lots of Republicans in charge in key states who could spot it if it did indeed happen.
For the purposes of this exercise, let's take the 11 most competitive states in the 2016 election — competitive either because they have been swing states in the past, or look like they're in that category today. On this list: Arizona, Colorado, Florida, Georgia, Iowa, Nevada, New Hampshire, North Carolina, Ohio, Pennsylvania and Virginia.
In these states, seven of 11 governors are Republicans — Democrats only have Colorado, New Hampshire, Pennsylvania and Virginia. And the administration of the elections are under GOP control — either via secretary of state or some other office — in eight of 11, according to the National Association of Secretaries of State.
There are just two of these 11 states, in fact, in which both are controlled by Democratic governors and chief elections officials: Pennsylvania and Virginia.
That means, if there is to be real election fraud in the states that matter, it will have to be performed almost completely under the noses of Republican officials who would both be responsible for it happening on their watch and would either not see it or have to cover it up, for some reason.
If you expand it out further, to all 20 states that The Fix currently rates as potentially competitive — adding in Alaska, Indiana, Maine, Michigan, Minnesota, Missouri, New Mexico, Utah and Wisconsin — Republicans control 13 of 20 governor's seats and control the election process in 12 of 20 states. And again, only Minnesota and Missouri have Democrats in charge of both. (Alaska has an independent governor and a Democratic lieutenant governor, who is the state's chief elections officer.)
Plenty of Republicans are already rebuking Trump's allegation that the election will be rigged at the ballot box, including Ohio Secretary of State Jon Husted, who called the charge “irresponsible.” Should Trump lose and refuse to concede because of alleged voter fraud, there will be a Republican of Husted's stature in place in nine of 11 key states and 15 of 20 competitive states to evaluate that claim. And so far, plenty of Republicans have been willing to speak out.
That may not stop Trump from arguing that these Republicans are part of the conspiracy against him. But it would make his claims a tougher sell.