Former senator of Pennsylvania and Republican presidential candidate Rick Santorum delivered a stark warning for President Donald Trump, as his administration was hobbled by a barrage of damaging news reports over the last 10 days.

"Unlike Democrats, who will never break with a president, no matter what they do — I mean I don't care, they can find him with a smoking gun and a picture, they wouldn't break with him — Republicans will," he said on CNN Friday night. "So I would say this to President Trump: This can't continue for a whole lot longer."

The White House has been attempting to deflect many of the reports that have revealed unflattering details about Trump's interactions with US officials and with foreign governments. Additionally, the Trump administration has attempted to quell accusations that Trump tried to squash multiple stories surrounding his campaign's ties to Russia — which largely involve his former national security adviser, Mike Flynn.

Santorum said Trump was hoping to "change the narrative" as he embarks on his first foreign trip as president, hoping it would "give some comfort to Republicans that he's actually interested in being president and doing something positive for the country."

Santorum also defended some of the controversial comments that Trump had made, including revelations that he referred to former FBI Director James Comey, who Trump fired earlier this month, as a "nut job" in a meeting with Russian officials.

"Where have you been in the past 18 months," asked Santorum. "I mean, come on!"

"This feigning of outrage ... this is who the American public elected — they elected someone who is outrageous at many times, and now, most of the time it seems like ... and it creates all sorts of incendiary remarks from those who don't like him."

Santorum ran in the 2012 and 2016 US presidential elections as a Republican nominee, eventually bowing out in both election years.