Both major political parties in the United States have cheated in previous presidential elections, a political analyst in Virginia says.

“Both sides cheat in American elections; Democrats and Republicans cheat and that’s been known for many years,” said Keith Preston, the chief editor of AttacktheSystem.com.

“There has been more blatant cheating in more recent times or it has become more obvious, particularly in this particular case involving the Democratic Party’s efforts to undermine the presidential campaign of Bernie Sanders,” Preston told Press TV on Tuesday.

He made the remarks after US Republican presidential nominee Donald Trump cast doubt over the validity of the result of the November presidential election.

Addressing his supporters in the city of Columbus, Ohio, Trump warned that the upcoming presidential vote might be rigged. “I’m afraid the election is going to be rigged,” he said. “I have to be honest.”

The billionaire businessman said he hears “more and more” that the November 8 vote may not be contested fairly.

He stated that the Republican primaries were slanted against him but his “landslide” victories helped him in overcoming the “fixed” system.

Last week, WikiLeaks released about 20,000 emails from the DNC that show top Democrats writing off Sanders’s chances during the primary presidential elections.

Trump suggested that the Democratic Party had fixed its primaries to help Hillary Clinton defeat Sanders in the race for presidential nomination.

“Trump is raising a valid issue, he’s raising the issue that the Democratic Party maybe trying to cheat in the upcoming presidential election as well,” Preston said.

“Donald Trump is very good at using controversial statements and sensationalism as a means of self-promotion, it’s really a big part of what he does,” he added.

According to a CBS News poll released on Monday, Clinton leads Trump by seven percent, 46 percent to 39 percent.

Meanwhile, a CNN-ORC poll released later on the same day showed that the former secretary of state was ahead of the business mogul by nine points.

A Gallup poll released early last month found that Trump and Clinton are among the worst-rated presidential candidates of the last 70 years.