Earlier on Monday, he filed official paperwork with the FEC to compete in the Republican primary. The initial filing for Kobach spelled his first name wrong, as "Chris," but an amended form was submitted to the FEC to change it to "Kris."
His entrance comes on the heels of a failed gubernatorial bid in 2018, when he lost to former state Sen. Laura Kelly, a Democrat, by 5 percentage points. Despite the staunch conservative aligning himself with the president, particularly with a hardline stance on immigration, securing the president's full-throated endorsement, and Trump traveling to the state for a Topeka rally a month before the general election, Kobach came up short as voters opted for his Democratic rival who captured endorsements from both sides of the aisle and touted a more moderate message.
In a state dominated by the GOP, where Republicans outnumber Democrats 2-to-1 according to the Kansas City Star, Kobach's 2018 defeat was seen as a blow to the party. As he now mounts a 2020 Senate candidacy, he faces an uphill climb against his own party amid rising concerns about his viability if he captures the nomination.
Earlier this year, in the wake of Roberts announcing his retirement at the end of his fourth term, Senate Majority Leader Mitch McConnell and other top Republicans urged Secretary of State Mike Pompeo to launch a bid for the seat instead, which would be a potential stymie to Kobach's nomination.
"I'd sure like for him to think about it," McConnell told Fox News in February. "The president's obviously happy with him being secretary of state. At some point, [Pompeo] might decide he wants a different job and I wanted him to know we'd all be behind him if he did."
Top party leaders see Pompeo, who previously represented Kansas in the U.S. House before taking his current post in the Trump administration, as a top contender to replace the the longtime senator. But before Kobach inched closer to announcing his bid, Pompeo distanced himself from those rumors in January.
In a Fox News interview, Pompeo addressed reports McConnell was urging him to join the Republican race, saying, "Lots of folks have reached out to me and suggested I ought to do that. I have suggested to them that I have a very full plate as Secretary of State, and I intend to keep doing this so long as President Trump will commit to it."
Asked if he would support a Kobach run, Pompeo said, "I’m so far out of politics. I think it might even be a federal violation if I answered that question, so I’m going to just say I appreciate your interest."
Despite Kobach entering the race with state-wide name recognition, the Senate GOP's campaign arm sees his candidacy as a risk to preserving their majority in the upper chamber.
"Just last year Kris Kobach ran and lost to a Democrat. Now, he wants to do the same and simultaneously put President Trump’s presidency and Senate Majority at risk," a spokesperson for the National Republican Senate Committee told ABC News. "We know Kansans won’t let that happen and we look forward to watching the Republican candidate they do choose win next fall."
The race to fill Roberts' seat is expected to be crowded, with two Republicans already vying for the nomination, including state Treasurer Jake LaTurner and former Kansas City Chiefs player, Dave Lindstrom. It is unclear if the president will wade into the 2020 Senate race, but Kobach's allegiance to Trump appears to be a pillar of his campaign.
Kobach told the room of supporters that he spoke to Trump "a few days ago on the Fourth of July on the subject of illegal illegal immigration," as he stood before a banner that read "build the wall."
"It became clear to me that the president needs someone who will lead the charge with him in the United States Senate," he said. "In the Senate, there really hasn't been anyone leading the fight. And that's part of the reason I decided to step forward. I would say if you look over the past two years and a half years that President Trump has been in office, there really hasn't been anyone in the Senate who has been pushing this agenda."
Earlier this year, Trump was considering Kobach for the position of immigration czar to coordinate immigration policy in the administration, according to the Associated Press, but the president ultimately chose former Virginia Attorney General Ken Cuccinelli.
Kobach also used his announcement speech to elevate his loyalist agenda to Trump, suggesting his involvement in the Trump administration's efforts to add a citizenship question to the 2020 U.S. Census, before condemning those across the aisle for their opposition to the move.
"It is true that I advised the president about putting a citizenship question back on the United States Census," he said. "It is something we have to do ... in part because we have a constitution requirement ... but the Democrats and the ACLU have really lost their mind on this issue."