A former White House national security official announced Monday that he is challenging GOP Rep. Tom MacArthur, who was instrumental in negotiating a key amendment to the Republican health care bill.

Democrat Andy Kim is a native of New Jersey’s 3rd District and served as the National Security Council’s director for Iraq during President Barack Obama’s administration. In Afghanistan Kim worked as a diplomat and strategic adviser to Gen. David Petraeus and Gen. John Allen in Afghanistan.

Despite his security credentials, Kim is also focusing on the Republican congressman’s role in crafting the GOP health care bill, also known as the American Health Care Act. 

“Last month, I watched Representative Tom MacArthur rush a vote on a dire healthcare bill without letting the American people understand the consequences,” Kim said in a news release announcing his campaign. “Under Trumpcare, tens of thousands of people in our congressional district will lose their healthcare. Nobody voted to send a representative to Congress to gut health care.”

Republicans signaled Monday that they would highlight Kim’s national security record in the Obama administration.

“Under Andy Kim’s watch, the United States failed to grasp the threat ISIS presented to the world and failed to formulate a strategy to stop them,” said Chris Martin, a spokesman for the National Republican Congressional Committee. “If that’s what Kim considers a record of success, what does failure even look like?” 

But MacArthur has faced criticism from his colleagues and constituents for his role in crafting an amendment to AHCA that helped appease conservatives, but raised concerns about protections for people with pre-existing conditions.

MacArthur resigned as a co-chair of the moderate Tuesday Group after the health care bill passed the House. He also faced angry constituents in a Democratic part of his district for nearly five hours. Health care dominated the town hall meeting.

The Congressional Budget Office estimated the House bill, which passed last month, would leave 23 million Americans without health insurance by 2026. The bill faces an uncertain future in the Senate, where a GOP working group is crafting its own health care legislation behind closed doors. 

Democrats view the health care fight as a salient campaign issue, and are zeroing in on Republicans who supported the AHCA. The Democratic Congressional Campaign Committee listed MacArthur as one of its 2018 targets.

Inside Elections with Nathan L. Gonzales rates this race as Solid Republican. President Donald Trump won the district by 6 points in November, according to calculations by Daily Kos Elections.