Justin Amash, a former member of the Republican Party turned Libertarian, has dropped out of the U.S. presidential race.

"After much reflection, I've concluded that circumstances don't lend themselves to my success as a candidate for president this year, and therefore I will not be a candidate," he wrote on Twitter.

Amash said the race for the White House presented "extraordinary challenges" for candidates outside the old parties.

The 40-year-old was seen as an independent thinker even during his time in the Republican Party. He supported the impeachment of President Donald Trump.

Amash has represented Michigan's 3rd Congressional District since 2011.

Before he declared his candidature for the November vote, Amash said Americans often settled for candidates simple due to their allegiance to the primary parties.

"I think it's important when we think about what we want in a president, we think about honesty and practicality and capability. And too often we're settling for candidates who don't represent those qualities, but are just the candidates who made it through their particular party primaries," he said last month.