The U.S. election campaign appears to have entered the so-called silly season, launched by a combination of offending tweets, October surprises and other assorted campaign-related controversies.

There are, of course, the usual reports of voting irregularities and accusations of voter fraud. In Florida for example, the FBI is investigating after Republicans claimed more than two dozen prominent members of the party received a letter questioning their eligibility to vote, the Washington Post reported.

And in Ohio and Wisconsin, civil rights groups, claiming voter intimidation, forced the removal of billboards in black neighbourhoods warning that voter fraud is a felony, the Post reported.

Meanwhile, the attack ads are swarming in swing states. Extreme anti-Obama ads are popping up in the crucial swing state of Florida, including some accusing the president of being a Muslim, the New York Times reports.

As well, a new anti-Obama DVD is being dropped into voters’ mailboxes claiming the president is the love child of his mother and Frank Marshall Davis, a Communist Party loyalist, the Times reported, while also noting the DVD producer had previously claimed to have tracked down Elvis Presley in the witness protection program.

Supporters of Obama have released their own anti-Bain ads and those that portray Romney as an extremist on abortion, the Post reported.

Trump's card

But real estate mogul, birther and Romney supporter Donald Trump definitely ramped the silly season up earlier this week with his promise of a bombshell announcement that would change the course of the election.

Rumours swirled as to what the announcement could be, but in the end, there were no stark revelations, only a pledge by the Donald to give $5 million to the president's choice of charity if he released his passport and college records.

Democrats and Republicans alike yawned and mocked, both taking time to tweet shots at Trump.

Not to be outdone, celebrity lawyer and Obama supporter Gloria Allred hinted at her own October surprise — an attempt to help make public testimony given by Romney in 1991 regarding the divorce case of Staples founder Tom Stemberg, a supporter of Romney's.

Although a judge on Thursday granted that request, a gag order remained on Stemberg's ex-wife, who wants to give the public her opinion of Romney, but can't unless the order is lifted.

Also competing for attention has been controversial conservative commentator Ann Coulter, who has come under fire for tweeting that during the final presidential debate, she approved of "Romney's decision to be kind and gentle to the retard."

Mixed endorsement

Meanwhile there's the brewing controversy around Senate hopeful Richard Mourdock, who said pregnancies that result from rape are "something God intended."

Romney's campaign has said he disagrees with Mourdock's remark, which came in a debate Tuesday with his opponent, Representative Joe Donnelly. But Romney is standing by his endorsement of Mourdock — and not asking the Indiana state treasurer to take down an ad Romney filmed Monday in support.

The Obama campaign has pounced, saying that "Romney must withdraw his support of Mourdock — who'd force rape victims to bear an attacker's child as 'God intended.'"

And now the president himself has grabbed some attention for a comment he made about his opponent in an interview with Rolling Stone magazine, according to an excerpt posted on Politico. Historian Douglas Brinkley wrote: "As we left the Oval Office, executive editor Eric Bates told Obama that he had asked his six-year-old if there was anything she wanted him to say to the president.

"She said, 'Tell him: You can do it.' Obama grinned.… 'You know, kids have good instincts,' Obama offered. 'They look at the other guy and say, "Well, that's a bullshitter, I can tell."'"

As media reporter Howard Kurtz, writing in the Daily Beast put it: "It’s the last two weeks of a presidential campaign: a time for suspense, for intrigue, for plot twists and … well, a whole lot of silliness."

With files from The Associated Press