Former two-term Massachusetts Gov. Bill Weld became the first Republican to mount a long-shot primary challenge against President Donald Trump. He announced his candidacy for president on April 15, 2019. The 2016 Libertarian vice presidential candidate told ABC News he would have been "ashamed" if he'd passed up on running against the president for the Republican nomination. Weld has touted his bipartisan record and ability to court independent voters in early voting states as his pathway to the White House.

Name: William "Bill" Floyd Weld

Party: Republican -- with a stint in the Libertarian Party from 2016-2019

Date of birth: July 31, 1945

Age: 74

Hometown: Smithtown, New York

Family: Weld has five adult children -- David, Ethel, Mary, Quentin and Frances -- with his first wife, Susan Roosevelt Weld, a great-granddaughter of Theodore Roosevelt. Now, Weld lives in Canton, Massachusetts, with his wife, author Leslie Marshall, and has three adult stepchildren.

Education: Weld graduated summa cum laude from Harvard College with a bachelor of arts degree in Classics in 1966. He received an international economics degree from Oxford University the following year, before returning to Harvard Law School and graduating in 1970.

What he does now: After announcing his candidacy, Weld took an unpaid leave of absence from Mintz Levin law firm. He is currently a member of the Council on Foreign Relations and an associate member of the InterAction Council. He also sits on the board of directors of cannabis company Acreage Holdings, alongside former House Speaker John Boehner, R-Ohio, and on the board of Just Energy Group Inc.

What he used to do: Weld ran as the vice presidential nominee on the 2016 Libertarian ticket. He served as governor of Massachusetts from 1991-1997. He previously served at least seven years as a federal prosecutor, first as U.S. attorney for the district of Massachusetts from 1981-1986 and then as U.S. assistant attorney general for the Criminal Division of the Justice Department from 1986-1988. Early in his career, Weld participated in the Watergate impeachment inquiry as legal counsel on the House Judiciary Committee.

Key life/career moments:

Weld began his legal career as junior counsel on the House Judiciary Committee's staff in the Watergate impeachment inquiry. After working as a staffer in Congress and then as a private attorney in Boston, President Ronald Reagan appointed Weld as U.S. attorney for the district of Massachusetts in 1981. Five years later, Reagan promoted Weld to assistant attorney general for the Criminal Division of the Justice Department.

Weld was elected governor of Massachusetts in 1990, becoming the first Republican to win a gubernatorial election in the state in 20 years. During his governorship, Weld cut taxes 21 times, led 16 international trade missions, oversaw six upgrades for the state's bond ratings, expanded abortion access and broadened LGBTQ rights, according to his campaign website. He was regarded as one of the most fiscally conservative governors in the country.

In 1996, Weld ran unsuccessfully for the U.S. Senate, losing to John Kerry. Weld resigned as governor in 1997 to pursue a nomination by President Bill Clinton as the U.S. ambassador to Mexico but withdrew his nomination after former Sen. Jesse Helms, R-N.C., effectively blocked it in committee. For the next decade, Weld worked a variety of legal and financial jobs including a stint as the chief executive officer of Decker College in Louisville, Kentucky. He re-entered the political sphere in 2005, in an unsuccessful bid for governor of New York.

Weld ran for vice president of the United States in 2016 on the Libertarian ticket with Gary Johnson. He returned to the Republican party in early 2019 when he announced his presidential exploratory committee.

Where he stands on some issues:

Weld has positioned himself as a Republican who blends fiscal conservatism with social liberalism. His campaign told ABC News that getting their candidate on a debate stage with the president is a top priority -- but that's unlikely to take place.

"The RNC and the Republican Party are firmly behind the president. Any effort to challenge the president's nomination is bound to go absolutely nowhere," a RNC spokeswoman told ABC News in July.

In his first 100 days in office, Weld said he would first tackle cutting spending and rebuilding relations with close U.S. allies.

Weld strongly opposes Trump's tariffs and his withdrawal from the Iran nuclear deal but has agreed with him on wanting to remove troops from Afghanistan, according to Axios. His website indicates that on the economy, Weld supports tax cuts and reigning in spending. On social issues, Weld supports gay marriage, abortion rights and marijuana legalization.

Weld's campaign website prioritizes the issues of "income inequality, debts and deficits, and climate change." He said he would have the U.S. rejoin the Paris climate accord.

Fundraising:

As of July 2019, Weld's campaign told ABC News that since entering the race in mid-April, they raised nearly $700,000 from 7,000 total donors. On top of supporter contributions, Weld gave at least $181,000 of his own money to the campaign, bringing the second quarter total to $869,000. The average donation for the quarter was $98, according to the campaign.

Weld reported $208,043 cash on hand following the third quarter deadline in mid-October.

During the 2016 presidential race, when Weld ran on the Libertarian ticket, he accepted donations from super PACs.

What you might not know about him:

In 1994, Weld was reelected as Massachusetts governor with 71% of the vote, the largest margin of victory in state history.

Weld's family traces its history back to America's early days, with one of his ancestors' graduating from Harvard College in 1650 and another, William Floyd, signing the Declaration of Independence.

Former special counsel Robert Mueller's sole federal contribution on record went to Weld in 1996 -- two checks totaling $450 during Weld's U.S. Senate race, according to the Center for Responsive Politics.

In his time between serving as Massachusetts governor and running for New York governor, Weld published three novels.

ABC News' Will Steakin contributed to this report.

Read more:

Bill Weld: Everything you need to know about the 2020 presidential candidate - ABC News