Washington (CNN) Soon after Donald Trump glided down the gilded escalator in Trump Tower, he shocked the world by announcing he was running for president and promised the political world a campaign steeped in controversy.

"When Mexico sends its people, they're not sending their best. They're not sending you. They're not sending you. They're sending people that have lots of problems, and they're bringing those problems with us. They're bringing drugs. They're bringing crime. They're rapists. And some, I assume, are good people," Trump said on June 16, 2015.

And with those words, Trump gave his nascent campaign its first notes of controversy, attracting a wave of media attention and in the process started to draw millions of disaffected voters to his unconventional campaign. The rambling 45-minute announcement speech exposed the foundation of Trump's campaign -- hard-line immigration and trade proposals bolstered by blustering rhetoric and a disregard for facts -- and drew up the battle lines that would define the election to come.

Two years later, Trump's political priorities remain largely unchanged. Though he has struggled as president to follow through on a slew of campaign promises he laid out in his announcement speech, Trump still talks of building a wall and making Mexico pay for it, he continues to decry imbalances in the US's trading relationships and he is still committed to repealing Obamacare.

While his political views remain controversial, President Trump is now shrouded in a controversy of an entirely different nature -- one that is growing more ominous by the day.

Facing a federal investigation targeting his campaign associates' ties with Russian officials during the 2016 campaign, Trump has lashed out publicly and privately in the months since he took office at what he's decried as a "witch hunt" while critics have accused Trump of acting improperly in firing the FBI Director James Comey and top US officials to publicly undermine the credibility of the Russia investigation.

You are witnessing the single greatest WITCH HUNT in American political history - led by some very bad and conflicted people! #MAGA — Donald J. Trump (@realDonaldTrump) June 15, 2017

Now, Trump is facing legal heat amid Comey's allegations that Trump pressed him to pledge his "loyalty" and asked directed him to stop the investigation into his former national security adviser Michael Flynn.

Trump has denied those accounts, but The Washington Post reported Wednesday that the special counsel overseeing the investigation into the Russia's meddling in the 2016 election is now also investigating whether Trump obstructed justice -- making clear that Trump's presidency -- much like his campaign -- will remain shrouded in controversy.

Live-by-controversy

But while the controversial rhetoric and campaign proposals that Trump first laid out in his 2015 campaign announcement propelled Trump to victory in the Republican primaries and ultimately sent him past the finish line in the November election, the latest swirl of controversy threatens Trump's very presidency.

As Trump jumped from one controversial proposal to another, pundits predicted his poll numbers would nosedive. Instead, they climbed steadily.

Trump's live-by-controversy mantra appears to have found his limits. As the controversy clouding his presidency has grown from allegations of collusion between his campaign associates and Russia to potential obstruction of justice on the part of the president, Trump's poll numbers have sunk, with his approval below 40% in the latest Gallup tracking polls.

The consequences are going beyond poll numbers, with the barrage of allegations he is facing on an at-times daily basis undermining his ability to implement his agenda -- the very agenda he laid out two years ago.

As Trump's approval rating closes in on the size of his political base, Trump's ability to stave off a further decline in his approval rating now becomes increasingly linked to his ability to make good on the promises he laid out in his June 16, 2015 speech.

"I would build a great wall, and nobody builds walls better than me, believe me, and I'll build them very inexpensively, I will build a great, great wall on our southern border. And I will have Mexico pay for that wall," Trump said then.

Trump took steps early in his administration to launch the federal government into the task of planning the construction of a wall on the US-Mexico border, but has yet to secure funding to build the massive wall he called for on the campaign trail and Mexico has shown no signs it will be willing to front the cost.

His promise to "immediately terminate President (Barack) Obama's illegal executive order on immigration" has languished as Trump has resisted repealing protections for undocumented immigrants who arrived to the US as children, but Trump's presidency has ushered in an increase in arrests of undocumented immigrants amid sweeping changes that give immigration officers wide latitude to arrest those living in the US illegally.

Trump in his opening pitch to voters also offered himself up as a scathing Iraq War critique, foreshadowing the opposition to "nation-building" policies he would emphasize on the campaign trail.

Trump has continued to disavow those types of policies, but he is handing more authority to the Pentagon in overseeing the conflicts the US is currently engaged in, all but assuring that the US will deploy thousands of more troops to Afghanistan, deepening its involvement there.

Trump hasn't lived up to his promise two years ago to "be the greatest jobs president that God ever created," but his presidency has injected consumers and the stock markets with new confidence in the economy, and unemployment has continued to steadily tick down.

The president's promises to rebuild the nation's infrastructure, impose 35% tariffs on companies that outsource their manufacturing to Mexico and force countries like Saudi Arabia to pay the US for its security umbrella -- all laid out in his kickoff speech -- remain little more than campaign proposals.

But even as the President struggles to implement many of his campaign proposals, he is sticking to the themes and rhetoric he laid out two years ago.

When he talks about infrastructure, he still draws comparisons between some of the US's dilapidated roads and bridges and the modern infrastructure he's seen abroad. He still rails against "lobbysts" and "special interests" and continues to promise he'll get the "great deals" done for the country. And just as he marveled then that his Trump Tower audience was "beyond anybody's expectations," Trump continues to tout crowd sizes as a measurement of success.

He has remained focus on the themes of his campaign, focusing on national security, trade and infrastructure as among the top issues driving his agenda.

During the campaign, the controversies he generated helped him draw attention to those planks of his campaign, as each new controversy brought more attention to Trump's campaign, more Americans tuning in for each rally.

Now, the controversies may simply be getting in his way.