(CNN) Friday is the last day for President Donald Trump's legislative director Marc Short, ending a whirlwind tenure of a tumultuous time between the executive and the legislative branch of government.

Short has seen Trump through accomplishments -- a tax cut law , a Supreme Court Justice confirmation -- and disappointments, such as the failure to fully repeal the Affordable Care Act, as well as a wild roller coaster of relationships to members of his own party on Capitol Hill.

"We certainly accomplished a lot that is sometimes overshadowed," Short told CNN in a recent interview, looking back on what his West Wing legacy will be, citing regulatory reform and judge confirmations. "You go back and think of things that you could have done differently. The failure to repeal (Obamacare) was certainly a disappointment. It was a disappointment that when given a chance to, that some wavered in that," Short said.

Short has led the Trump White House's legislative affairs team since the transition -- and has witnessed an evolution in the President's relationship with congressional leadership. A year ago, Trump fired off a few days of critical tweets directed at someone who is supposed to be one of his closest Republican allies.

"Can you believe that Mitch McConnell, who has screamed Repeal & Replace for 7 years, couldn't get it done. Must Repeal & Replace ObamaCare!" one such tweet read.

Nowadays, the President and the Senate majority leader work more harmoniously.

"My sense is that the two of them have a much better working relationship today and respect each's role," Short said, adding there's a lot that "we feel we've all accomplished together." He calls McConnell a "champion on regulatory acts."

At his departure, Short was praised for his work on Capitol Hill by congressional leaders, including by House Speaker Paul Ryan.

"Marc was a great partner in helping Republicans advance major tenants of our legislative agenda including regulatory and tax reform and the rebuilding of the military," the Wisconsin Republican said in a statement to CNN. "I thank him for his service and wish him all the best in his next chapter."

Short says he's seen a lot of change in the past 18 moths he's worked at the White House but one of the biggest changes he's seen in the relationship between Trump and Republicans on Capitol Hill involves Twitter.

"I would say that one of the biggest changes of the last 18 months is that members used to call and say, Can the President stop tweeting?" Short said. "And those same members call today and say, 'Can the President tweet this for me?' So where we were 18 months ago with the social media is very different than today that the members now call and specifically ask for tweets."

Short weighs in on McCain-Trump feud

One spat with a member of Congress has deteriorated even further: the relationship between Trump and Arizona Republican Sen. John McCain, who, even while being in his home state of Arizona recovering from cancer treatment, still publicly criticizes the President. On Monday, McCain referred to Trump's news conference with Vladimir Putin -- where Trump appeared to back Putin over the US intelligence community -- as "one of the most disgraceful performances by an American president in memory."

Short reflected on what was probably one of the most salient McCain moments from Trump's presidency: The Arizona Republican's vote against repealing Obamacare in July 2017.

"When in post-midnight hour it ended in the dramatic way that it did, it certainly was disappointing," Short said, adding, that since then, "It's not as if Senator McCain has stopped expressing his disappointment with President Trump."

The outgoing legislative affairs director told CNN that he has personal relationships with people who advise McCain and that he would reach out to those contacts during contentious points.

Trump's invites to the White House pay off

Short said several times during the phone call interview to CNN that the President has forged relationships with members in a way that he claims Trump's predecessor Barack Obama did not: by inviting members to the White House for lunches, dinners, movie nights and even bowling sessions.

Short said that the Obama administration bluntly admitted a pitfall of their administration to him as he assumed the role of legislative affairs director: "He [President Obama] did not fully utilize what the White House offers. He was obviously a very gifted orator ... but using the allure of the White House and having members of Congress over, it was not something that was fully utilized"

Those smaller gestures, Short says, were the ones that went "unnoticed" or unreported by the press.

"Democrat members of Congress say to me that they were over at the White House more times in the first part of the Trump administration than they were in the whole eight years of Obama White House," he said.

Trump and immigration

Perhaps one of the most elusive, recent targets in Congress has been immigration. Republicans in both chambers struggled with and ultimately did not pass legislation to address the expiring Deferred Action for Childhood Arrivals program , full funding for Trump's campaign promise of a border wall or the issue of family separation at the border.

During the the most recent round of immigration debate in the House, Trump publicly supported an immigration bill, then reversed on which immigration plan he supported . He appeared to change position several times and Republican members of Congress were dumbfounded.

"#CHANGETHELAWS Now is the best opportunity ever for Congress to change the ridiculous and obsolete laws on immigration. Get it done, always keeping in mind that we must have strong border security." Trump tweeted in June.

A few days later, the President tweeted, "Republicans should stop wasting their time on Immigration until after we elect more Senators and Congressmen/women in November. Dems are just playing games, have no intention of doing anything to solves this decades old problem. We can pass great legislation after the Red Wave!"

In the days surrounding the House immigration votes earlier this summer, Trump faced criticism -- from members of his party own party -- for what they considered erratic support for efforts by GOP leadership to push a compromise bill on immigration. Short explained Trump's stance bluntly

"I understand where the House members are coming from but the President's perspective was, If this is such a difficult issue and one that is demagogued easily," he said, asking, "Why twist people's arms if the Senate is never going to pass it and it's never going to reach my desk?"

A new legislative director takes over

As he hands the reins over to Shahira Knight , who has been serving as the deputy director of the National Economic Council at the White House, Short has confidence that "transition should be rather seamless for her and the team."

Knight worked closely with the President on the tax cut bill, and Short says she has a "significant amount of Hill experience" from working on the House Ways and Means Committee earlier in her career. He describes Knight as "an incredibly bright person."

"I think there's a lot of continuity," Short said. "She understands the process well."

Ryan also praised Knight whom he'd work with on the tax bill.

"Shahira played an important policy role during the crafting of our tax reform plan and I look forward to working with her on our larger legislative agenda," Ryan said in his statement to CNN.

Short will be a research fellow at the Miller Center at the University of Virginia and teaching at the business school at UVA, in addition to partnering with a friend in a consulting firm.

If those options don't work out, Short could have a future as a pundit. In a White House where television trumps all, Short also became a prominent face of the administration, appearing on Sunday morning political shows, local syndicate stations and cable news outlets with regularity. He said the appearances helped him in more ways than one.

"It was a not a role that I honestly thought would be a component. It has pluses and minuses. There are some members who when they see you as the face of the administration, they give you more attention and access."

It also helped him with the boss -- Short told CNN that Trump would notice his television appearances. When asked if Trump was pleased with Short's media performances, he responds, "I probably think if he wasn't I wouldn't have been doing them."