Democrats hope to turn Iowa from red to blue.
The investigation began in Des Moines, the capital of the state of Iowa; A state that voted mostly for Republicans in the last election, and the Democrats hope to turn it from red to blue this time.
At the same time, the US mid-term elections are a test of Donald Trump's performance in his second term as president.
Dissatisfaction with the economic situation and the increase in the cost of living is one of the most important concerns of voters. Democrats hold the Trump administration responsible for America's economic problems, while Republicans reject those criticisms, saying that voting for Democrats means supporting extremists.
So far, 58 million Americans across the country have participated in early voting; A figure that is considered a record for early participation in mid-term elections in the United States.