Amid apparent presidential campaign missteps, former Florida Gov. Jeb Bush is hoping that releasing a new book could revive his hopes of securing the Republican nomination. His polling has dropped in recent weeks, and national attention has focused on whether or not the man who was once seen as an almost inevitable nominee for his party had fallen over an edge he couldn’t climb back up.

But, whether or not the new book, titled “Reply All,” manages to revive his campaign, releasing a book as a presidential candidate can bring in a lot of cash to a candidate’s personal bank account. From Bush to Florida Sen. Marco Rubio to former Secretary of State Hillary Clinton, the candidates can make a good bit of money from the books they write to pump up their public image as they seek the nation’s highest office.

Retired neurosurgeon Dr. Ben Carson, who is battling it out at the head of the Republican pack for first place in national and state polls, is said to have earned somewhere between $8.9 million and $27 million from book royalties and paid speeches in the 16 months prior to his campaign announcement. Clinton, for her book detailing her time as secretary of state during the first half of the Obama administration, received $5 million in royalties.

But not everyone gets as much as Carson or Clinton, even if they’re one of the top contenders in the 2016 race. Rubio, who is currently in third place among Republicans in averages of polls put together by Real Clear Politics, received a relatively small amount – though still quite a bit compared to the average American's yearly income -- for his books. Altogether, Rubio made somewhere between $100,001 and $1 million off of book royalties in 2015, according to Federal Election Commission (FEC) filings for his presidential run. Filings with the FEC and Senate for personal finances of candidates and politicians are structured in ranges. However, Rubio’s total is said to be in the middle of that range.

Coming in at fourth place, Sen. Ted Cruz's book royalties are about in the same range as Rubio’s. His recent reporting indicates that he made at least $318,750 for his book “A Time for Truth.” His filing indicates that he hadn’t made more than $1 million.

Bush, who has considerable personal wealth, did not list any royalty income in his 2015 personal financial disclosures provided to the FEC. He made roughly $27.7 million between 2007 and 2013.