President Donald Trump told a roaring crowd Tuesday night at his latest Make America Great Again (MAGA) rally — this one in Council Bluffs, Iowa — that “if you want to drain the swamp, you must defeat the Democrats” in November’s midterm election.

“Democrats are the party of crime. Republicans are the party of safety,” Trump said to another packed house after doing four similarly rousing rallies last week in Minnesota, Tennessee, Mississippi and Kansas.

“Drain the Swamp” was one of Trump’s signature campaign promises in 2016, referring to reducing the size, power and cost of the federal government.

Trump is taking an unusually active role for a first-term president in the first midterm congressional election of his tenure. Republicans control both the Senate and House of Representatives, but Democrats are thought to have a solid chance of regaining a majority in the lower chamber in the November 6 election.

“In their lust for power, the Democrats have become totally unhinged. They’ve gone crazy.”

If Democrats do retake the House, they could launch new investigations of Justice Brett Kavanaugh, and also of allegations that Trump campaign aides colluded with Russian interests during the 2016 presidential campaign.

House Minority Leader Nancy Pelosi (D-Calif.) has also indicated Democrats would seek to repeal the Trump tax cuts approved in December 2017 and credited by the president and congressional Republicans for the now-booming U.S. economy.

Trump said Democrats’ opposition to Kavanaugh’s confirmation last week was because they “were on a mission to resist, obstruct, delay, demolish and destroy. They wanted to destroy that man. Of course, they want to destroy me, too, but that’s all right. Me, we understand. Him? How can you do that?”

Democrats “just want to destroy everything, that’s all they’re good at. Their goal is to resist. Ours is to create. What the Democrats did to Brett and his beautiful family is a national embarrassment, a national disgrace.”

Trump mocked “the phony protesters that got paid” and reminded his enthusiastic supporters that “in just four weeks, you will have the chance to render your verdict on the Democrats’ outrageous conduct.”

He also mocked Sen. Dianne Feinstein (D-Calif.), the ranking minority member of the Senate Committee on the Judiciary, who rambled and hesitated when Sen. John Cornyn (R-Texas) asked her during the Kavanaugh hearings if she or a member of her staff leaked the allegations of Christine Blasey Ford that Kavanaugh sexually molested her when both were at a high school party in 1982.

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Related: Trump Takes Kavanaugh Victory Lap During Topeka MAGA Rally

The crowd began chanting, “Lock her up! Lock her up,” a chant previously heard at MAGA rallies when Trump has mentioned former Secretary of State Hillary Clinton.

Trump repeatedly encouraged the crowd to vote in the midterms, including taking advantage of Iowa’s early voting law, which permits residents to vote weeks in advance of the November 6 balloting.

“In their lust for power, the Democrats have become totally unhinged. They’ve gone crazy,” he said.

“Never forget that in 2016 we had the greatest movement in the history of our country,” he said to cheers. “With your vote, you can do so much.”

As expected, Trump also announced that he is directing his administration to allow year-round use of ethanol in gasoline used by automobiles, trucks, tractors and other internal-combustion engines.

“We’re going with E15 year-round. I made that promise to you during the campaign. I made that promise to you during the primaries,” Trump declared, drawing sustained applause. “Promises made, promises kept,” he said, beaming.

Under present regulations, gasoline with 10 percent ethanol is sold nationwide year-round, but another variety with 15 percent ethanol can currently be sold only during the summer months. The regulatory term for that mixture is E15, and automakers initially resisted it partly because converting engines to run on richer ethanol mixtures required numerous changes in materials and design.

Ethanol is refined from corn, which is a major crop for Iowa, so expanding the richer blend to the whole year should provide a significant boost to the Midwestern agricultural economy. Trump had promised during the 2016 presidential campaign to expand the use of ethanol.

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