His term as president was marked by allegations of corruption and accusations of a coup d'état, as well as the declaration of a state of emergency and a suspension from parliament by the Nauruan Supreme Court in 2008.

He initially played Australian rules football for the local team the Aces, but opted to pursue the sport of weightlifting.

Since Nauru had no Olympic Committee at the time, he successfully applied for Samoan citizenship and was allowed to compete for Samoa.

In March 2008 moves in the Parliament of Nauru to unseat the Administration of Marcus Stephen by means of a vote of no confidence were thwarted by the resignation of the Speaker, Riddell Akua.

[15] Unrest on the island which involved threats to export trade and the torching of a police station were events which occurred shortly prior to Parliamentary moves to remove President Stephen and his Administration from office.

On 22 March, the Speaker of the Parliament of Nauru, David Adeang, called a Parliamentary session, allegedly without informing government ministers, who therefore did not attend.

Opposition MPs, Adeang included, constituted a majority of legislators present, and passed a ruling outlawing dual citizenship for Members of Parliament.

[17] President Marcus Stephen accused Adeang and the Opposition of passing the ruling "after dark on Easter Saturday", "under candelight".

The Stephen Administration, in response, denied the claim of a coup d'état, stating that they were awaiting a ruling from the Supreme Court on the issue.

President Stephen and the eight other members of the 18-member Parliament who supported his Administration were suspended from the Parliamentary sitting, amidst rowdy scenes, by the Speaker, David Adeang, who had difficulty in making himself heard when commenting on the recent Supreme Court decision regarding dual nationality for MPs.

[22] On 18 April 2008, Stephen declared a state of emergency and called a snap election to end months of political deadlock.

In late 2009 or early 2010, the Stephen Cabinet rejected a proposed loan from Australian company Getax, which buys Nauruan phosphate.

Following the trip, the latter three defected to the opposition, and the Stephen government's parliamentary majority shrank from twelve-six to nine-all, leaving Parliament deadlocked.

[27][28] Following "repeated unsuccessful bids by the opposition to lodge motions of no confidence in the government of Marcus Stephen", early elections were held in April 2010.

The government officially reported that it was continuing its functions in a transitory capacity, in accordance with articles 16 and 20 of the Constitution, until a President could be elected by a majority in Parliament.

[34] A few days later, after "Australian officials ha[d] confidentially expressed concern to the government of Nauru over Getax's alleged role in the destabilisation" of the country, Stephen's government asked Australia to investigate "the activities of Getax and any financial ties it may have with politicians in Nauru", namely members of the opposition.

Stephen, and Justice Minister Mathew Batsiua, asked for an Australian investigation into money allegedly paid by Gatex to members of the opposition, which they suggested might constitute bribes.

Nauru's Director of Public Prosecutions stated there had been "attempts to bring about a change of government by bribery of members of parliament", and Stephen released documents "showing opposition members on salaries of less than $150 a week spending significant sums of cash on boats, cars, voters and trips".

In response to the request, the Australian Federal Police began an investigation into the allegation that Getax had bribed Nauruan opposition MPs.

Marcus Stephen was duly re-elected President, with a workable parliamentary majority, defeating Milton Dube by eleven votes to six.

Stephen remained in opposition until June 2012, when he was given the portfolios of Commerce, Industry & Environment, Nauru Phosphate Royalties Trust, and Fisheries in Dabwido's new Cabinet.