Trump rallies in North Dakota, says next SCOTUS pick should serve '40, 45 years' The rally in Fargo was his second campaign event this week.

FARGO, North Dakota -- President Donald Trump returned to the campaign trail Wednesday in North Dakota, the site of one of this cycle's most pivotal and competitive U.S. Senate races.

The rally, which took place at an arena in Fargo, also came just hours after the retirement announcement of U.S. Supreme Court Justice Anthony Kennedy. Trump wasted no time in addressing the topic of Kennedy's retirement, saying he hopes to get a new justice confirmed as soon as possible.

"Justice Anthony Kennedy, a very special guy, just announced a little while ago, his retirement from the United States Supreme Court," Trump said, "We have to pick one that’s going to be there for 40 years, 45 years, we need intellect, we need so many things. So many elements go into picking a Supreme Court justice."

The president also cast the vacancy on the court as a critically important issue in the upcoming midterm elections.

"Democrats want judges who will rewrite the Constitution, any way they want to do it, and take away your Second Amendment, erase your borders and throw open the jailhouse doors, and destroy your freedoms," Trump claimed. "We must elect more Republicans; we have to do that."

Trump also took a victory lap the day after the nation's highest court upheld his administration's travel ban.

"Just yesterday the Supreme Court upheld the travel ban, and our authority to keep America safe," Trump said to cheers from the crowd of thousands packed in the arena.

The president also took aim at Democratic Sen. Heidi Heitkamp, who is up for re-election this cycle and is facing a tough bid against GOP Rep. Kevin Cramer, who easily won the Republican primary to take on Heitkamp earlier this month.

“We need Kevin Cramer to replace liberal Heidi Heitkamp," Trump said.

Trump said Heitkamp "went to Washington and immediately joined Chuck and Nancy," referring to Senate Minority Leader Chuck Schumer, D-N.Y., and House Minority Leader Nancy Pelosi, D-Calif., "and now they have a new leader, Maxine Waters.”

Cramer in turn told Trump and the crowd, "You never have to wonder where I’ll be, because I’ll always be with them and with you 100 percent of the time, thank you, god bless you, welcome to North Dakota."

Trump also attacked Heitkamp for her votes against the GOP tax bill and against legislation to address so-called "sanctuary cities," that he claims protect illegal immigrants.

"You need a senator that doesn't just talk like they're from North Dakota, you need a senator that votes like they're from North Dakota," Trump said.

"Heidi and every single one of the Democrats voted against our tax cuts," Trump added.

Heitkamp released a pointed statement following the rally.

"I don't answer to a political party or president, I only answer to North Dakotans who deserve an independent voice in the Senate," she said. "That's why I've always been eager to work across the aisle -- including with the president -- to get results for our state, and today's rally hasn't changed that."

Heitkamp is one of 10 Democrats up for re-election this cycle in a state Trump won in the 2016 presidential election.

Trump also decried "radical Democrats" that are calling for the abolishment of the U.S. Immigration and Customs Enforcement (ICE) in recent days following the controversy over his administration's "zero-tolerance" enforcement policy that led to the separation of some immigrant children from their families after attempting to illegally cross the U.S.-Mexico border.

"The only response they will find from our government is very strong law and order," Trump said, "We will not tolerate attacks on our law enforcement. We will protect our law enforcement like they protect us."

Trump also slammed Democratic Rep. Joe Crowley, D-N.Y., who Tuesday night became the first incumbent in the party to lose a primary this cycle.

"One of my biggest critics ... Joe Crowley, got his ass kicked, by a young woman who had a lot of energy," Trump said of Crowley, who was rumored to be a potential Speaker of the House candidate to replace Pelosi. "I was disappointed in a way when he got beaten because he was going to take her place. Politics is a mean game isn’t it? It’s a fleeting game."

Trump touted low unemployment numbers, rising wages, manufacturing enthusiasm and progress on veterans issues in a broad pitch to voters less than six months out from the November elections, the first major contests since his inauguration.

Trump also did not hesitate to relitigate the 2016 presidential election.

"When is she going to get over it," he said of his former presidential rival Hillary Clinton, to chants of "lock her up," from the crowd.

"We weren't expected to win, but every time I'd go out we'd have crowds like this," Trump said fondly of his time on the campaign trail in 2016, recounting visits to the key swing states of Michigan and Wisconsin, which were key to his victory.

Ahead of Wednesday night's rally in North Dakota, Trump tweeted that Cramer "is an extraordinary Congressman who will hopefully soon represent this great state as your Senator."

The rally marked the third time in the last week Trump has campaigned for Republican candidates. On Tuesday he rallied with South Carolina Gov. Henry McMaster, who won a runoff election Tuesday, and last week he was in Duluth, Minnesota in a key House district with a retiring Democratic incumbent the GOP is aiming to flip in November.

Trump's popularity in the North Dakota is unquestionably strong. His 36-point margin of victory in the state in 2016 was only surpassed in size by his win in West Virginia, where he won by more than 40 points.

The political realities of the state are not lost on Heitkamp, who relies on her bipartisan credentials and personal appeal in the state, and has not been afraid to tout her working relationship with President Trump and maintain a measured distance between herself and the brand of the national Democratic Party.

In a recent campaign ad Heitkamp boasted about cutting Environmental Protection Agency regulations and voting for a border security bill.

"With Washington so divided, Heidi is a rare senator who doesn’t get bogged down by partisan politics – she knows both sides of the aisle have good ideas," Libby Schneider, Heitkamp's campaign manager wrote in a statement accompanying the ad, "Heidi brings small-town North Dakota common sense to the Senate, and that’s why she’s been successful getting real results for the folks she serves."

Heitkamp's campaign confirmed to ABC News that the senator was not in the state during President Trump's rally because the U.S. Senate is currently in session.

Cramer, a three-term congressman and former state party chair who was personally urged by President Trump to run against Heitkamp, is attempting to paint her as an "out-of-touch liberal," and points to her support of 2016 Democratic presidential nominee Hillary Clinton as evidence.

"Senator Heitkamp’s wild support for Hillary Clinton and her out-of-touch policies show exactly why she has no business representing North Dakotans in the U.S. Senate,” said Tim Rasmussen, communications director for Cramer’s campaign, "In recent weeks, Senator Heitkamp has attempted to convince North Dakotans of her conservative ideals and her alleged allegiance to President Trump. But North Dakota voters know better."

Looming large over the race is the threat of a major trade war over the Trump administration's tariff policy that could hurt North Dakota's substantial farming community.

According to the U.S. Department of Agriculture, soybean production generated over $1.1 billion in revenue for North Dakota in 2016.

Trump defended his administration's tariff policy at Wednesday night's rally.

"Taking advantage of the United States is over," Trump said.

"The forgotten men and women of our country are forgotten no more," Trump said as he praised the people of North Dakota.

"We will never, ever stop fighting for our freedom. As long as we are proud of who we are, and what we are fighting for, we will never fail. With your help, with your voice, with your vote, we will win, win, win," Trump told the crowd in the conclusion of his wide-ranging speech.

"Together we will make America wealthy again. We will, and are, making America strong again...we will make America loving again. And we will make America great again. Thank you North Dakota," Trump said.