A key architect of the House GOP-passed American Health Care Act Rep. Tom MacArthur, R-New Jersey, is now officially facing a challenge in New Jersey's Third Congressional District.

Andy Kim, a former National Security Council staffer who advised President Obama on Iraq, formally announced his run for Congress Monday after attending various town halls across the district and raising over $50,000 dollars on a crowdfunding site for political campaigns, Crowd Pac.

Time for the people to have a voice—I'm officially running against TrumpCare 2.0 author Tom MacArthur! https://t.co/0zhPwMQ6rp — Andy Kim (@AndyKimNJ) June 19, 2017

Kim previously advised Mr. Obama on counterterrorism efforts including the ongoing fight in Iraq and the war against the Islamic State of Iraq and Syria.

Get Breaking News Delivered to Your Inbox

Kim, 34, is running primarily on stopping what he calls "Trumpcare 2.0," GOP efforts to repeal and replace Obamacare. He has directly criticized MacArthur for his role in crafting amendments to the AHCA. In a written statement announcing his run, Kim said that MacArthur is "hopelessly out of touch" with New Jersey families.

MacAthur's amendment to the House GOP healthcare plan would allow states to obtain a federal waivers to the ACA rule requiring sick and healthy people to be charged the same premiums. If the House GOP version passes, the change could have a significant impact on consumers who live in states where the waivers are granted. While consumers would still have to be covered under the AHCA, those with pre-existing conditions could see their premium costs rise if they don't have continuous health coverage. MacArthur has said those consumers with pre-existing conditions would be covered by high-risk pools.

The American Healthcare Act would give states $100 billion over the next decade to help with high-risk pools.

Kim told CBS News he decided to explore a run for Congress the day MacArthur released his amendment.

"In New Jersey, we have an estimated 3.8 million non-elderly people who have pre-existing conditions, over 300,000 just in the Jersey 3rd District. MacArthur didn't just vote for TrumpCare, he wrote it. He needs to be held accountable," said Kim.

While Republicans celebrated after the bill's House passage at a White House ceremony with Mr. Trump, MacArthur faced a very different crowd back home.

In May, a group of protesters outside a MacArthur town hall in New Jersey lay on the ground with tombstones during a die-in, while inside, MacArthur answered heated questions about the health bill and President Trump. Some Kim supporters chanted "goodbye" to MacArthur, referring to his 2018 race against Kim.

"I hear people calling their congressman an idiot," MacArthur said. "I wonder, really wonder, how any one of you would perform in Congress."

MacArthur said he came to the Democratic part of the 3rd Congressional District for his first town hall since the health care bill passed because he wants to represent both sides and he's aware of the "anxiety" over health care.

MacArthur has since resigned as the co-chair of the moderate Tuesday Group, citing division with the group, saying many members were unwilling to compromise over the most recent health care debate.

"More than half of the no votes for the AHCA came from Tuesday Group members, despite almost every one of our members voting numerous times to repeal the ACA," MacArthur said in the letter announcing he was stepping down. "Arguably we have a Congressional majority because of this very issue. Frankly, inaction on healthcare was a non-starter for me, and it should be for our entire party. We owe it to the American people who elected us to fix the Obamacare mess. Just because it's hard cannot become an excuse to do nothing."

Kim said that while he doubts the health care bill will successfully pass in the Senate, the focus should remain on whether more Americans are covered, as well as out-of-pocket costs for Americans

"We need an open and deliberate process that gives the American people information, CBO scores, expert testimony in public hearings," said Kim in response to Republicans closed-doors meetings on the health bill. "The rushed process of the House vote and the MacArthur Amendment goes against what is best for the American people."

When asked what was his biggest challenge was in facing MacArthur, Kim said "I just want to make sure I have the opportunity to connect with as many people as I can in the district to talk to them about my to growing up in the Jersey 3rd, my work as a public servant, and how I want to work with them going forward."

He added, "It's a large district and I want to make sure my message is getting across and I have the opportunity to define myself."

According to the New York Times, Kim is hoping to use fellow Democrat Jon Ossoff's run in Georgia's special election for the state's 6th Congressional District as a model for his own race, hoping to harness the same energy Ossoff and the party is projecting behind the candidate.

Kim believes the 3rd District, which voted twice for Mr. Obama, is "looking for someone who will represent them specifically."

"MacArthur isn't from the District and moved there when he saw a political opportunity," Kim said. "He sees the Jersey 3rd as a stepping stone. I see it as home. I want to represent everyone in the District."