The abrupt decision by House Republicans to abandon their bid to gut the independent Office of Congressional Ethics not only averts a PR disaster for the party as it prepares to take full control of Washington. It has also revealed the ability of the unpredictable Donald Trump to change politics here with a tweet.

Hours after the surprise vote on Monday to remove many of the watchdog’s powers – a vote of which no prior word was given – the president-elect strongly criticised its timing, if not its substance, on Twitter. The OCE might be “unfair,” he said. But “do they really have to make its weakening their number one act and priority?

Focus on tax reform, healthcare and so many other things of far greater importance!” Mr Trump added the hashtag DTS, ‘Drain The Swamp,’ evoking his campaign promise to clean up Washington.

The tweet hits the problem on the head. This was supposed to be a day highlighted by the swearing in of the new 115th Congress, and a swift and public start to dismantling the Obama legacy, starting with the Affordable Care Act, or ‘Obamacare.’ Instead, had the OCE changes gone ahead, it would have been dominated by a move that would further tarnish the already abysmal reputation of Congress, and an approval rating barely out of single digits.

In fact, the OCE, set up in 2008, has drawn anger from both Republican and Democratic Congressmen who have been its targets, for the watchdog’s over-zealous investigations and its reliance on anonymous outside tips.

But at the closed door meeting where the decision was taken, the two top House Republicans, Speaker Paul Ryan and majority leader Kevin McCarthy, urged their colleagues to drop the idea, arguing that it could only put Congress in the worst possible light, making it look like an insider body out to protect the interests of its members. To no avail. The Republican rank and file that had caused enough trouble in the previous Congress, once again refused to follow the leadership’s advice – until Mr Trump’s intervention by Twitter.

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Thus far, the president-elect’s efforts at swamp-draining have been less than impressive. Lobbyists are as influential as ever. He has appointed the personally wealthiest cabinet in history, and seems oblivious to the countless potential conflicts of interest between his official duties and his business interests. But the OCE affair offers a glimpse of how Mr Trump is not going to play by the old rules of Washington, and of the unpredictable consequences that might follow.

The episode is also a sign of how the goals of Mr Trump and the new Congress are not perfectly aligned. After six years of frustration at Barack Obama’s veto pen, House Republicans have been champing at the bit to unleash their agenda on the country.

In some respects this agenda coincides with that of Mr Trump, including the swift repeal of Obamacare, de-regulation, and cuts in taxes as well as reform of the tax code. But in others it does not – most notably Mr Ryan’s ambitions of sweeping reforms in entitlement programmes like Social Security, Medicare and Medicaid, which the President-elect has indicated should not be touched.

Overshadowing everything is the issue of Russian hacking of the 2016 election, where Mr Trump is virtually alone in his dismissal of the unanimous conclusion of US intelligence agencies that Moscow was involved. Key Capitol Hill Republicans, notably Senate Armed Services committee chairman John McCain, are pressing for a full and bipartisan Congressional investigation.