Real estate tycoon Donald Trump, right, and Wisconsin Gov. Scott Walker confer during a break in the Republican presidential primary debate on Aug. 6 in Cleveland. (Mandel Ngan/AFP via Getty Images)

Scott Walker's presidential campaign underwent a reboot last week, and the Republican governor from Wisconsin is now aggressively going after Donald Trump's supporters, many of whom are frustrated with career politicians. The shift has been anything but subtle — and Walker often appears to mimic the flashy billionaire, who is leading in early polls.

Here are six changes that I have noticed, especially in the past week:

1) The career politician is now slamming the Republican Party.

One of the theories explaining the rapid ascent of Trump — the straight-talking, politically incorrect reality television star who has never held elected office — is that voters are tired of traditional politicians and want someone radically different.

Walker has long pitched himself as a Washington outsider who can bring some Midwestern common sense and niceness to the White House — but he is far from being a non-politician. Walker has been campaigning for various offices since college and has spent nearly all of his adult years in an elected position. In Wisconsin, he is a polarizing figure who is loathed by many Democrats and adored by many Republicans, who partnered with him to severely weaken public unions in the state, a fight that catapulted Walker into the national spotlight and enabled him to run for president.

Last week, Walker started slamming fellow members of his party. He criticized Republican members of Congress for not repealing Obamacare or pushing through immigration reform. He passively slammed Republican governors who expanded Medicaid in their states. He even went after Republicans at home.

Republican presidential candidate Scott Walker unveiled a new health-care proposal that calls for repealing Obamacare. (Reuters)

"I had to take on the establishment, my own party, many of whom were very reluctant to challenge the status quo and didn’t want to push the big, bold reforms that we pushed," Walker told a small audience at a Maid-Rite restaurant in northern Iowa last week. "And we took them on.”

Some Republicans at home were — unsurprisingly — confused and angered by the remarks. This week, Walker tempered his comments and now says that he had to face down only "a handful" or "a few" or "a couple" of Wisconsin Republicans who didn't share his vision.

2) Walker has added China to his list of countries that are not friends of the United States.

Walker's announcement speech on July 13 largely followed the same talking points he has used for months — except he suddenly had harsh words for China, a country Trump has been slamming for months. Walker has said the United States needs to push back against China's cyberattacks, advances into international waters and "abysmal record when it comes to human rights, particularly the persecution of Christians and others."

Walker upped his anti-China rhetoric on Monday, amid stock market turmoil, by demanding that President Obama rescind a state dinner invitation to Chinese President Xi Jinping. Walker told reporters: “Why would we be giving one of our highest things a president can do... at a time when all of these problems are pending out there?"

[Scott Walker: Obama should show ‘some backbone’ by canceling Chinese state visit]

In 2013, Walker traveled to China for a 10-day trade mission — his first as governor — that included hawking Wisconsin-grown ginseng, riding a Harley-Davidson motorcycle at a newly opened dealership and meeting with Xi.

3) Walker wants a wall on the border just like the wall Trump wants on the border, only better. 

Like many GOP candidates, Walker has long said that the United States needs to secure its southern border. But since his branding reboot, Walker has been much more exact: He wants a wall, just like Trump. Walker has added that such a wall would need proper staffing and the latest technology. His blueprint: the 500-mile fence separating Israel from the West Bank that he inspected during an overseas trip this spring.

4) Walker wants to end birthright citizenship, too. Oh, wait, scratch that.

Walker ran into trouble last week when he warmly embraced Trump's immigration plan, saying it is "very similar to his own." Among the various proposals presented by Trump, Walker seemed to agree that it is a problem that illegal immigrants are coming to the country and having children, who automatically become U.S. citizens.

While at the Iowa State Fair last week, Walker said he would "absolutely" support the end of birthright citizenship. But it turns out that birthright citizenship, granted in the U.S. Constitution, is something that many constitutional purists don't want to see changed. On Friday, Walker said he no longer had a position on the issue. On Sunday, he said he opposed changing the constitution. On Monday, he said that his position on this issue has been "pretty consistent."

[A timeline of what Scott Walker has said about birthright citizenship]

5) Walker's attacks on the media have sharpened.

Sure, Walker has long accused reporters of twisting his words — but he's still a media-savvy candidate who throws around television industry jargon, talks political strategy during lengthy radio interviews and closely follows coverage of his campaign. As Milwaukee County executive a decade ago, Walker would often write his own news releases and blogged about his annual motorcycle tour of the state, obsessing over how much coverage it garnered. At the Iowa State Fair, Walker held off starting a news conference until he confirmed that all the video cameras were trained on his face: "Okay, let's see, I can see that one, that one, that one. That one's a little tougher over there."

Trump is notorious for colorfully ripping apart reporters, so Walker seems to have upped his game. I followed him around South Carolina for about 10 hours on Monday and heard these criticisms: Only "folks in the media" think his campaign is not performing well. Only the media cares about his stance on birthright citizenship. The media has incorrectly reported that Trump's supporters are angry when, Walker says, they simply want urgent action. When asked whether Wisconsin Republicans have pushed back against Walker's characterization of their opposition to his reforms, he said that "some of the media tried to gin that up a little bit." The media has forgotten that there are still troops serving in dangerous places.

Walker also complained Monday that he is not getting as much media coverage as Trump has received: "Just because the media covers some candidates more than others doesn't mean the rest of us aren't talking about things. It's just that we don't get the same level of coverage."

6) Walker appears to be dressing more professionally.

Trump is notorious for overdressing for the occasion. He wore a blazer during a visit to the border and bright white shoes to the Iowa State Fair. He's a billionaire — one who owns planes and helicopters, mansions and resorts — and he doesn't pretend to be anything less.

Walker has aggressively pitched himself as an average, middle-class Midwestern dad who understands what it's like to carry tens of thousands of dollars in credit card debt, eat fast food for most meals, fly commercial and bargain-shop at Kohl's. As Walker announced his candidacy at a county fair ground exhibition hall in the Milwaukee suburbs, his two college-age sons wore suits and ties, but the candidate skipped the tie and rolled up his sleeves. At candidate forums over the past few months, Walker has often dressed far more casually than his rivals.

[Scott Walker's all-American diet — pizza, burgers and lots of barbecue]

Something seemed off Monday. Walker was wearing a starched white shirt with a blue tie, which he left on even as he toured a valve-making factory in North Carolina and stood outside in the sweltering sun. And over the course of four appearances in two states, there was no mention of bargain-shopping at Kohl's.