President Barack Obama's recent domestic and foreign policy accomplishments indicate that his ambitious agenda is coming to fruition. By contrast, Senator John McCain, Obama's opponent in the 2008 election, appears to be selling his political soul in an effort to survive a tough Republican primary challenge in Arizona. Their dichotomous current realities are reflections of how they managed their respective presidential runs.

In the case of Obama, he began preparing himself to save the US economy even before he got to the White House. During the last half of 2008, when the US financial institutions were in freefall, the president-to-be consulted the country's top economic decision-makers and other trusted advisers on a daily basis – sometimes for hours. Today, although the recession is not over, Obama's administration has arguably saved the country's economy from total collapse – just like he said he would.

The president also achieved monumental legislative victories in his first 15 months in office. He signed into law a bill reforming the US healthcare system and revamped the US federal student loan programme – just like he said he would.

In the foreign policy realm, the ink is still fresh on a new nuclear arms control treaty with Moscow – a big step toward "resetting" the US-Russian bilateral relationship – just like he said he would.

Earlier this month, Obama played host to 47 world leaders in Washington to discuss how the global community can secure the world from nuclear terrorism. The Nuclear Security Summit was the largest meeting among world leaders since countries came together in San Francisco to discuss the founding of the United Nations in 1945. One of the outcomes was an agreement to secure or destroy hundreds of thousands of tonnes of weapons-grade nuclear fuel by the year 2014. Obama has also positively changed the tone on the international arena and sharply improved the US image around the world – just like he said he would.

Senator McCain, on the other hand, is on the verge of being ousted in his party's primary election in Arizona this August. McCain is facing a serious challenge from a former talk-show host, JD Hayworth, who charges that McCain is not conservative enough to represent the Grand Canyon state. Hayworth calls himself the conservative candidate, a branding that seeks to win over the more passionate, more conservative, more-likely-to-go-to-the-polls voters. These probable voters, many which associate themselves with the Tea Party movement, are part of the far right wing of the Republican party – the wing of the GOP that McCain despises.

Ironically, the rise of this far-right bloc in American politics, which now threatens the war hero's political career, is partially McCain's own fault. McCain's panicked last-minute decision to choose Sarah Palin to be his vice-presidential running mate is backfiring on McCain and other moderate Republicans. The half-term Alaskan governor is not the founder of the Tea Party movement, but she fuels it with phony and uninformed slogans at the events.

McCain's choice for vice-president may prove to be the biggest political blunder of his entire career – a decision made without proper vetting in a last-ditch attempt to revive a campaign lacking both money and message. Choosing Palin was no doubt a bridge to nowhere for McCain, while it provided a radical, political near-nobody with a national platform during and beyond the election. Palin has endorsed McCain's re-election campaign, but the initial bump in the polls her support brought almost immediately levelled out.

And the senator is doing himself no favours by reversing his position on a slew of important policy issues and rejecting his status as an independent-minded political warrior. His out-of-character behaviour has resulted in ridicule even from old admirers. The Daily Show's Jon Stewart recently mocked McCain for changing his positions on the "don't ask, don't tell" policy of the US military, on redistribution of wealth and on embracing far right political figures that he previously denounced. Stewart also questioned the state of McCain's soul after Newsweek quoted the four-term Senator saying, "I never considered myself a Maverick."

The ironic twist for McCain is unfortunate, coming after decades of admirable service, first in the US military and later as an elected official. Throughout his political life, McCain was frequently the voice of reason across the political spectrum. Now, however, he has pulled out all the stops to tailor his message to the ultra-conservative primary election voters – a group that he used to disagree with almost as much as he does with the left wing of the Democratic party. At times, the 73-year-old has even retreated to infantile tantrums. After the end of the heated healthcare reform debate, McCain threatened that Obama should not expect any GOP co-operation for the rest of the year. Such language is more in line with the partisan hacks, the very same from whom he spent his political career differentiating himself.

The trajectory between a winner and a loser in presidential politics will naturally differ. McCain's case is, however, tragic because he seems to have lost much more than an office in the process. Early retirement, a shattered legacy and being partly responsible for the greatest radicalisation of American political discourse in recent history could ultimately be the result of McCain's 2008 presidential attempt.

Obama's presidency, on the other hand, continues to soar. His current mission is to overhaul US financial regulations; if successful, Obama will have accomplished another major objective on his ambitious agenda – just like he said he would.