Unable to break out of the bottom tier of candidates in the race for the Democratic Party nomination for President, Sen. Cory Booker (D-NJ) announced Monday that he was ending his bid for the White House, just three weeks before the first votes are to be cast in the Iowa Caucuses.

"I've made the hard decision to suspend my campaign for President," Booker told supporters in an email, as he announced that he is suspending his campaign.

While Booker has maintained an active campaign schedule, his poll numbers nationally have been in low single digits for months, as he has been unable to qualify for recent debates, making it even more difficult for him to attract support.

Six Democrats will debate on Tuesday in the final Iowa debate - but Booker was not going to be on the stage.

Booker had tried hard in recent weeks to continue organizing in Iowa as he made campaign stops around the Hawkeye State.

"If you’re interested in volunteering with our campaign—everything from calling voters from home to knocking doors in Iowa—please join our team!" Booker's campaign tweeted over the weekend.

“I can't wait to get back on the campaign trail,” Booker said, as he vowed to strongly support his party's nominee.