His name will not be on the ballot, but President Donald Trump will be there in spirit when Americans vote in midterm elections in November.

And the results will set the tone for the remaining two years of the presidency of the man who will be on everybody's mind.

Americans will vote nationwide on November 6 for the first time since the New York real estate tycoon pulled off one of the most stunning upsets in US political history.

Former president Barack Obama put Trump front and center in the opening salvo in a series of campaign stops Friday, accusing him of "capitalizing" on "fear and anger."

"What happened to the Republican Party?" Obama asked, taking off the gloves after nearly two years of avoiding direct criticism of his successor.

All 435 seats in the House of Representatives are up for grabs along with 35 seats in the 100-member Senate and the posts of governor in around 30 states.

Republicans currently hold majorities in both the House and the Senate. Democrats are hoping that a "blue wave" will propel them to victory in the House and the latest polls give them a good chance of doing so.

Seizing control for the Senate looks less likely.

In a Washington Post/ABC News poll of registered voters, 52 percent said they favored the Democratic candidate over the Republican candidate in their district. Thirty-eight percent said they favored the Republican.

As for the economy -- often a harbinger for the ruling party's fortunes -- 58 percent said it was "excellent" or "good" with 38 percent saying it was "not so good."

Unemployment is currently at an 18-year low at 3.9 percent while gross domestic product grew 4.2 percent in the second quarter.

'Soft favorites'

Despite the bright economic numbers, the "Grand Old Party" is struggling in large part because of the unpopularity of Trump himself.

The president -- whose time in office has been marked by frequent turmoil -- has been hit by an especially bruising week, with an anonymous op-ed alleging that members of his administration were seeking to frustrate his "worst inclinations" and head off disaster for the country.

That account was corroborated by investigative journalist Bob Woodward's new book, which describes a coalition of like-minded aides plotting to prevent the president from destroying the world trade system, undermining national security and sparking wars.

Larry Sabato, director of the Center for Politics at the University of Virginia, said that while Democrats are "soft favorites" to take the House, fortunes could change.

"Unforeseen events could wipe out their prospects before Election Day," Sabato said. "I don't expect that to happen, but the Trump era is tumultuous."

Midterm elections are traditionally difficult for the party in the White House as the president tries to respond quickly to the often unrealistic demands of the electorate.

Two years after Obama's election, Democrats suffered a bruising midterms defeat amid a bitter debate over health care reform.

Only once since Harry Truman was president has the party in the White House picked up seats in the House during a first term -- in 2002, in a United States which was still suffering the aftermath of the September 11, 2001 attacks on New York and Washington.

'Trump, Trump and Trump'

For many, the midterm vote is being seen as a referendum on Trump, whose style and personality sharply divides Americans.

"The top three issues are Trump, Trump, and Trump," said Sabato. "Since Trump is at 40 percent or so in the polls, this can't be good news for Republicans."

Trump in recent weeks has been trying to galvanize his base, holding high-energy campaign rallies in a bid to create a "red wave" of his own.

The president plans to step up campaigning in the next few weeks including a visit to Texas to support Senator Ted Cruz, once his bitter rival for the Republican presidential nomination.

Trump is well aware that a hostile Congress could severely limit his ability to get anything done during his remaining two years in office.

If Democrats take over the House, they could seize upon the various scandals surrounding his presidency and tie up his administration with myriad committee investigations.

Whatever the result in the congressional midterms, on November 7, Americans will begin looking to the next big election -- the November 3, 2020 presidential vote.

Trump, who will be 74-years-old by that time, has already rolled out his campaign slogan: "Keep America Great."

His Democratic challenger has not yet emerged and a fierce battle is expected to see who will carry the banner.

Trump, for his part, is feeling confident.

"It looks like they're going to have a lot of people lining up," he told the Daily Caller. "But so far, and I'm an honest guy, I'll let you know if there's anybody I see that could be trouble.

"But so far, I'm not seeing it."