Unlike his sister and brother-in-law, Donald Trump Jr. does not have an official post inside his father's White House. But the president's eldest son is carving a role in the new administration as an attack dog against Democrats and the media.

Trump Jr., 39, took the helm of the family business, along with his brother Eric, while their father is president. But he has not shied away from politics. Instead, he has become particularly active in the Republican Party, coordinating with the national committee, hosting fundraisers, campaigning for candidates. And he is prolific on social media, particularly Twitter, aggressively defending his father and condemning the president's critics.

Trump Jr.’s activity has raised speculation that his role in politics may evolve beyond that of a loyal son. While he has said he would not run for governor of New York in 2018, he hasn't ruled out entering the political fray someday. For now, though, his position outside the political realm allows him a different kind of platform.

"His conservative street cred makes him a favorite among the grassroots, and his willingness to get right to the point with his commentary makes him a favorite with the president's supporters," said Jason Miller, a former spokesman for the Trump campaign. "He has a very big following on social media, but also he's the president's son. If he's out there drawing attention to an issue, folks are going to pay attention."

This week, Trump Jr. focused his attention on CNN, his father's favorite foil, by tweeting a series of posts with the hashtag CNNBlackmail. He lambasted the network for its coverage of a controversial Reddit user who created a video of Trump Sr. body slamming a CNN logo, which the president then tweeted.

CNN's K-File reported that it had identified the video creator, and that the person, who had also posted anti-Semitic pictures, issued a lengthy apology and pledged not to post similar content again. The report indicated CNN would withhold the identity of the user if he kept his word.

Donald Trump Jr. seized on the fallout, accusing the network of threatening a 15-year- old Internet meme creator. When CNN countered that the Reddit user was an adult male, and not a child, Trump Jr. responded: "So blackmailing adults is ok?"

He also tweeted an article by the pro-Trump site Gateway Pundit, which highlighted Wikileaks founder Julian Assange accusing CNN of committing a crime.

In addition to media criticism, the younger Trump also trained his ire at Democrats this week. On the Fourth of July, for example, he tweeted:

Out of curiosity, what exactly are Big Govt, opprressive taxation, anti 2A left wing socialists celebrating today? — Donald Trump Jr. (@DonaldJTrumpJr) July 4, 2017

And when New York City Mayor Bill DeBlasio announced Thursday he would attend the G20 summit in Hamburg, Germany, Trump Jr. weighed in:

NYC mayor goes to G20 to protest against capitalism while the City's education, infrastructure etc rots under his "progressive" stewardship! https://t.co/B2W1q8qh0c — Donald Trump Jr. (@DonaldJTrumpJr) July 6, 2017

The younger Trump has 1.7 million Twitter followers, far fewer than his father's 33 million. And even as president, Trump tweets without a filter and often against protocol. His statements on social media, of course, garner far more attention and carry far more weight than his son's. But the younger Trump serves to amplify his father's message, and even, at times, acts as a backup. For example, he tweeted in his father's defense throughout the testimony of fired FBI Director James Comey on Capitol Hill last month, as the president stayed remarkably silent, per the suggestion of aides.

In an interview with ABC News last month, Trump Jr. said the investigation into allegations of collusion between Trump associates and Russian officials "reads and smells like a witch hunt." Asked in the interview about his father's administration, Trump Jr. said he believed there were people in Washington, including "plenty" of Obama-era holdovers, who were not working in his father's best interest.

"Frequently, what you see Don Jr. articulate on social media is what supporters are thinking but don't have those channels to get it out," Miller said. "Even if Don is charging ahead and operating on his own beliefs, there's a very good likelihood they are echoing similar sentiments in the White House."

Beyond social media, Trump Jr. has ingratiated himself with the Republican Party. And in some ways, he resonates with conservatives in ways his father can’t. He is an avid hunter and a National Rifle Association member, for example, and has particular appeal in the West. Trump Jr. campaigned twice for now-Montana Rep. Greg Gianforte, who was charged with assaulting a reporter on the eve of the election. GOP campaign officials expect to see him out on the trail during the midterms.

Trump Jr., along with his brother and sister-in-law, met with Republican National Committee leaders to discuss politics and the 2018 midterm elections. The RNC coordinates with the Trump children on news events, sharing talking points and social media and digital strategy, a spokesperson said. In addition to campaigning in Montana, Trump Jr. brought in $400,000 for the Indiana GOP through a fundraising event. In March, he headlined a fundraiser with Sen. Ted Cruz for the Dallas County GOP in Texas, raising $500,000.

Trump Jr. was active on the trail in 2016 for his father, raising money and delivering a prime-time address at the GOP convention in Cleveland. And like his father, he took on controversy. He came under fire on several occasions, comparing Syrian refugees to Skittles, for example, and evoking the Holocaust image of a gas chamber to describe the media's treatment of Republicans.

Trump Jr. and his brother Eric also have plans to expand the family hotel business beyond their typical clientele and into areas of the country where the pair spent time on the campaign trail, an endeavor that could blur ethical lines. Their involvement in politics has also raised eyebrows about conflicts of interest.

Eric Trump has continued to give interviews, and his wife Lara is active on the campaign trail. But Don Jr. has developed a particular enthusiasm for it. In a speech at the Dallas fundraiser, he recalled how he missed the campaign life.

"I thought I'd be going back to my regular job. I thought I'd be really excited about it. But once you get a little bit of a taste of that action, it's hard to leave ... it's like a great fight, the intensity." he said. "I don't miss the politics, I promise. I want nothing to do with the politics, but I miss the intensity of that."