Republican Conference Chairman John Thune of South Dakota reported assets of between $173,000 and $596,000.

Senator Marco Rubio, a Florida Republican and prospective 2016 presidential candidate, received $800,000 in royalties from Penguin Group USA Inc. for his 2012 memoir, “An American Son.” He reported a potentially negative net worth, with assets of between $259,000 and $860,000 and liabilities of between $450,000 and $1 million.

Student Loans

He paid off his remaining student loans of between $100,000 and $250,000.

“When I finished school, I owed over $100,000 in student loans, a debt I paid off just a few months ago,” Rubio said in February as he delivered the official Republican response to President Barack Obama’s State of the Union address.

The youngest U.S. senator, freshman Democrat Chris Murphy of Connecticut, and his wife each owed between $15,000 and $50,000 in student loans, his report showed. Murphy, 39, reported assets of between $70,000 and $225,000.

Freshman Senator Elizabeth Warren, a Massachusetts Democrat and Harvard University emeritus professor, and her husband Bruce Mann, a Harvard law professor, reported assets of between $3.8 million and $10.2 million. Most of it was in TIAA-CREF funds, including one valued at between $1 million and $5 million.

Book Money

Warren received $59,417 from Aspen Publishers for a series of books, including “Bankruptcy and Article 9” and “Secured Credit: A Systems Approach,” and $103 in royalties from Yale University Press for “The Fragile Middle Class.”

Senator Ted Cruz, a Texas Republican elected last November, took a pay cut to come to Washington. He was paid $1 million last year by his law firm. He reported assets of between $2.2 million and $5.1 million, including an $843,000 loan to his campaign as of Dec. 31, 2012.