COUNCIL BLUFFS, Iowa — President Trump delivered a harrowing campaign pitch to voters here Tuesday, four weeks ahead of the midterm elections.

Democrats, the president thundered to an arena crowd of roughly 9,000, are “radical,” “unhinged” and “dim” — an “angry left-wing mob” that would destroy people’s businesses, provide sanctuary to murderous immigrant gangs and plunge the nation into “poverty” and “chaos.”

“The Democrats have become too extreme, and they’ve become, frankly, too dangerous to govern,” Trump said. “They’ve gone wacko!”

For a president who campaigned on and is governing with themes of grievance and fear, the portrait painted Tuesday night in Council Bluffs was especially dark.

President Trump and GOP senators are framing Democrats as a "mob," after the opposition to Brett Kavanaugh, and hoping to energize conservatives against them. (Jenny Starrs/The Washington Post)

Trump’s 76-minute stemwinder before a roaring crowd of Iowans and Nebraskans in this border town along the Missouri River was a preview not only of his campaign blitz over the next 28 days, but also of his own reelection push that will begin in earnest soon after the midterms.

The president charged, for instance, that Fred Hubbell, the Democrat challenging Iowa Gov. Kim Reynolds (R), intends to “massively raise your taxes,” “take away your ethanol” and “devastate your farms and businesses.”

Hubbell has said he supports ethanol development though has criticized Trump’s “devastating trade war.”

And Trump reveled in calling Democrats “Dems,” only he pronounced it as “Dims,” an apparent play on their intelligence. He said he picked up the nickname from “the great Lou Dobbs,” whose Fox Business Network show the president watches regularly. Trump gave shout-outs at the rally to more than a half-dozen Fox News Channel stars, including Sean Hannity, Tucker Carlson, Laura Ingraham and Jeanine Pirro.

Trump claimed victory throughout — not only for the confirmation of Supreme Court Justice Brett M. Kavanaugh after a bruising nomination fight, but also for new trade deals, the falling unemployment rate and December’s tax cuts.

“The only reason to vote Democrat is if you are tired of winning,” Trump quipped.

Trump said the sexual assault allegations against Kavanaugh were “a national embarrassment” and the product, he argued, of a Democratic campaign to “destroy that man.”

“In four weeks, you will have a chance to render your verdict on the Democrats’ outrageous conduct,” Trump said, hoping to keep his conservative base energized through Election Day.

Trump singled out Sen. Dianne Feinstein (Calif.), ranking Democrat on the Senate Judiciary Committee, and accused her of disclosing the identity of Christine Blasey Ford, who had written a confidential letter this summer detailing her claims against Kavanaugh. Feinstein has denied that she or her staff leaked Ford’s name to the press, but Trump insisted she had.

“Did she leak that? One hundred percent,” Trump said. “I don’t want to get sued, so 99 percent.”

The crowd burst into chants of “Lock her up!” — a Trump rally staple usually reserved for demeaning Hillary Clinton, Trump’s 2016 Democratic opponent. Moments later, the crowd again chanted “Lock her up!” — this time when Trump invoked Clinton in his remarks.

Even as his rally crowd thundered for the imprisonment of two Democratic politicians, Trump said it was the Democrats who were the party of lawlessness.

“You don’t give power to an angry left-wing mob,” Trump said, warning that if Democrats win congressional majorities next month, they would “turn our country so fast into Venezuela.”

Trump took his crowd on a tour of his greatest hits against prominent Democrats. He mockingly called Sen. Richard Blumenthal (D-Conn.), a frequent cable-news critic of Trump, “DaNang Dick,” a reference to the senator overstating his military service during the Vietnam war several years ago.

Trump singled out Sen. Elizabeth Warren (D-Mass.) for particular disdain. Democrats, he said, “have gone so far left that they consider ‘Pocahontas’ a rational person. No, it’s crazy! Elizabeth Warren. Oh, I hope she runs.”

“We can finally get down to the fact as to whether or not she has Indian blood,” Trump continued, adding, in a mocking tone, that “her mother says she has high cheekbones.” Trump said Warren’s claims of Native American ancestry have given her unfair advantages in her career.

Warren has said those claims are based on family lore. But a Boston Globe investigation last month found that her ethnicity did not actually help her advance in her law career.

Tuesday night’s event was the first of several “Make America Great Again” campaign rallies scheduled for this week. Trump plans to visit Erie, Pa., on Wednesday and then rally supporters in Ohio and Kentucky on Friday and Saturday, respectively. Last week, he headlined rallies in Tennessee, Mississippi, Minnesota and Kansas.

Trump has already visited Iowa three times as president. He won the state by nine percentage points in 2016. But 56 percent of Iowans now disapprove of his performance as president, while only 39 percent approve, according to an Iowa Poll conducted last month.

Council Bluffs sits on Iowa’s western edge, across the Missouri River from Omaha, and Republican officials and candidates from Iowa and Nebraska attended the rally. There was a clear Nebraska tint to the audience, which at one point burst into chants of “Go, Big Red,” a reference to the University of Nebraska’s football team. When Trump asked attendees to cheer to identify their state of residence, the screams from Nebraskans were louder than those from Iowans.

Trump used the event to announce that his administration will press forward with plans to promote the use of ethanol, in a move that could boost Republicans on the ballot across the Midwest.

The announcement paves the way for year-round sales of E15, or fuel that is 15 percent ethanol by volume. Currently, such sales are prohibited during the summer months because of air pollution concerns.

“Today, we are unleashing the power of E15 to fuel our country all year long,” Trump said, to big cheers from the crowd. He noted that he “made that promise to you during the primaries, remember? Promises made, promises kept.”

Sonmez reported from Washington.