Ivanka Trump has been accused of violating the Hatch Act, which bans government workers from speaking out on political campaign issues, over a tweet she wrote before her father’s 2020 presidential campaign launch.

The influential Washington-based watchdog Citizens for Responsibility and Ethics in Washington (Crew) has filed a complaint against Donald Trump’s daughter, a senior presidential aide who works in the White House as an adviser, albeit unsalaried.

In a letter to the Office of Special Counsel (OSC), part of the Department of Justice, Crew said her tweet, posted on Father’s Day last weekend, just a few days before Trump’s re-election campaign launch in Florida, included his 2016 campaign slogan “Make America Great Again” and claimed “the best is yet to come”.

The tweet in question reads: “Four years ago today, I introduced my father @realDonaldTrump when he launched a Campaign that would forever change America. Because of his courage, Americans are safer and more prosperous…and the best is yet to come!” She signed off the tweet with the words “Happy Father’s Day!” and an emoji of the American flag.

Accompanying the message was an image from the June 2015 event at Trump Tower when Trump launched his presidential run that shows her applauding her father to the backdrop of a campaign banner emblazoned with her father’s name and now infamous slogan.

Four years ago today, I introduced my father @realDonaldTrump when he launched a Campaign that would forever change America.



Because of his courage, Americans are safer and more prosperous...and the best is yet to come!



Happy Father’s Day! 🇺🇸 pic.twitter.com/ygcbg3URQx — Ivanka Trump (@IvankaTrump) June 16, 2019

Crew also claimed she had used her government Twitter account, which has more than 6.5 million followers and on which she describes herself as “adviser to Potus” to share “multiple partisan political posts” since March last year.

In the letter to the special counsel, Henry Kerner, dated 20 June 2019, Crew’s executive director, Noah Bookbinder, requests that the OSC investigate Ivanka Trump and says she “violated the Hatch Act by using her social media account”.

It reads: “These actions were directed specifically toward the success or failure of Donald J Trump, a candidate in a partisan election. By sharing these posts on a Twitter account that Ms Trump uses for official government business, Ms Trump engaged in political activity prohibited by law.”

It also cites OSC social media guidance, which states that federal employees “may not engage in political activity while on duty or in the federal workplace”.

The president’s daughter, who on Thursday attended the launch of the 2019 Trafficking in Persons Report with the US secretary of state, Mike Pompeo, has yet to comment on the claims.

Bookbinderadded: “It has become clear that this rampant abuse of public office is not a problem of one bad apple but rather a key feature of the Trump White House.”

He said: “By blatantly using her office for politics right after the Office of Special Counsel recommended her colleague be fired for repeatedly acting similarly, Ivanka Trump has basically thumbed her nose at the OSC and the rule of law. Never before have we witnessed this level of illegal politicized behavior, and it must not be allowed to continue.”

The “colleague” refers to Kellyanne Conway, who serves as a counselor to the president.

The complaint comes just a week after the OSC called on the president to fire Conway over multiple violations of the Hatch Act.

The OSC criticized Conway in a report addressed to Trump as a “repeat offender” of the Act and claimed she had “shown disregard for the law”.