|Dr. Arthur Welton|
|Played by:||Jim Holmes|
|First episode:||"Day 6: 5:00pm-6:00pm"|
|Last episode:||"Day 6: 11:00pm-12:00am"|
After an assassination attempt was made on President Wayne Palmer, he was rushed down to the medical center in the presidential bunker. Welton and his team operated on Wayne, who was in critical condition. Wayne had surprisingly strong vitals for his condition, but he needed to be put into a chemically induced coma in order to stay stabilized.
Karen Hayes later confronted Welton and asked about Wayne's condition. When Karen asked if Wayne could be brought back to consciousness, to handle a matter of National Security, Welton highly advised against it. Bringing Wayne out of his comatose state could cause permanent damage. Welton also told Hayes that he would need consent from a family member, particularly Wayne's sister Sandra, who was present at the bunker.
Less than an hour later, Welton was confronted by Karen and Sandra. Sandra told him that she wanted her brother brought out of the induced coma. Welton told her that Wayne would face serious complications if he was brought out of the coma. Welton realized that this was the only way to stop a third World War, so he followed Sandra's wishes. When Vice President Noah Daniels demanded for Welton to keep Wayne in the coma, Welton told Daniels that he had no authority over him.
Shortly after Wayne was brought out, complications started to begin, but Welton and the nursing staff were able to prevent this. Before 12am EST (9pm PST), Wayne was conscious and he called off the nuclear strike. When Wayne tried to get out of his wheelchair, Dr. Welton advised against it. Wayne was convinced that he needed to stand in order to look like a strong leader, despite Karen's point that President Roosevelt did a fine job in a wheelchair.
After Wayne asked for a shot of adrenaline, Welton gave it to him and escorted him to the Cabinet meeting. Vice President Daniels had the 25th Amendment activated, and Welton presented the medical argument to the Cabinet and Attorney General Graves. Welton was convinced that President Palmer will not suffer from any further complications, and he would make a full recovery.
After Daniels withdrew his plan of having Palmer removed from office, President Palmer asked Welton to come into his office. Palmer asked for another shot of adrenaline, and Welton was convinced this could cause serious complications. When Wayne told Welton he would find another doctor to do it, Welton injected the drug into Wayne's arm.
Around 1:30 AM EST, Palmer collapsed in his office, and Tom Lennox called Welton to reexamine him. Welton advised the President that he might be suffering from vascular damage induced by the adrenaline and urged him to return to Medical for his own sake. Palmer refused, insisting that he needed to return to work, and ordered Welton to administer another shot; the doctor told the President that he would resign before he did so and endangered Palmer's life.
After Abu Fayed was killed and the Russian Suitcase Nukes were secured, President Palmer gave a press conference. During the conference, he began to stutter, and eventually collapsed. Welton went to the Oval Office and informed Vice President Daniels, Karen, Tom, and Lisa Miller that Palmer had suffered from a cerebral hemorrhage. Welton advised them that he didn't expect Palmer to regain consciousness anytime soon, and that he would know the full extent of the damage after Palmer had been transferred to Bethesda for an MRI scan. The 25th Amendment was put back into immediate effect.