Republican presidential candidate Donald Trump stated unequivocally on Sunday that the US election is rigged.

"The election is absolutely being rigged by the dishonest and distorted media pushing Crooked Hillary," Trump tweeted.

It's not the first time Trump has claimed the US electoral process is biased against him — it has been a recurring theme throughout his campaign. Recent polls have shown that many of his supporters now doubt that votes will be tallied fairly in November.

Trump’s statement on Sunday was met with heavy skepticism, including from officials in his own party, who dismissed suggestions that they will not see November's results as legitimate.

“We will absolutely accept the result of this election,” vice presidential candidate Mike Pence told "Meet The Press" on Sunday.

Daniel Murphy, an elections expert with Democracy International, says that while the US could benefit from certain electoral reforms, claims of election "rigging" — like the kind that takes place in other countries — are far-fetched.

Murphy, who has served as an election observer in several countries, says that during elections in Kosovo in 2010, for example, he and other monitors "saw a lot of ballot-stuffing." Employees in charge of counting votes were also "paid off to manipulate the data after the ballots were cast." Regulations in the US make similar action here nearly impossible, he says.

Another common tactic for manipulating elections, Murphy says, is for a powerful political party to silence critics. When Egypt held elections in 2014, "There was no ability of anyone who disagreed with [President Abdel Fattah] el-Sesi and his message to have any fair platform."

But it's impossible to argue that something similar is happening to Trump, Murphy says. "The [US] media absolutely has given him the opportunity to speak."

Meanwhile, concerns about widespread election fraud are unfounded, Murphy says. In part, that's because hundreds of different government entities are responsible for administering the election, at both the state and local level. It would be incredibly difficult to get so many groups — which are composed of representatives of both political parties — to work together.

"You would have to have a very large conspiracy to pull that off," Murphy says.

So the claim that the US election is rigged against Donald Trump, "is not something that keeps me up at night at all,” Murphy says.