There are a lot of candidates who have announced that they are seeking a nomination for the presidential election (especially Republicans) this year. Those candidates can be seen on this site under Democratic Candidates and Republican Candidates, including those who have dropped out of the race. However, in the following, an overview of potential candidates who opted not to run will be presented:
Joe Biden: The current Vice-President was expected by many to enter the race despite being in his 70s (born in 1942). However, a personal tragedy was behind the VP’s decision not to run. Biden ran for President in 1988 and 2008, both times unsuccessfully, however, he cam on the ticket with President Obama in 2008 as VP and won. He was considered to have been able to mount a severe challenge to the only two serious Democratic contenders for the nomination at this stage, Sanders and Clinton.
Sarah Palin: She was the running-mate of Republican presidential nominee John McCain in 2008 and could have been the first female VP in the US. Before then she was the Governor of Alaska and have since been a TV personality. Although, Palin was rumored to run both in 2012 and now, she does not have the same momentum or popularity as she had eight years ago, which probably is the factor behind her decision not to run. Furthermore, few would think she would have a realistic chance of winning the nomination in 2016.
Mitt Romney: The Republican nominee for President in 2012 is not seeking to regain his name on the ticket after losing the General Election to President Obama. The 68 years old Romney has announced that he is not running for President a third time (he also ran in 2008) and it is difficult to predict whether he would be successful again after losing the General Election last time. He has already proven that he can win a Republican nomination, but many in the party were disappointed with his campaign in the General Election.
Elizabeth Warren: The Massachusetts Senator have been urged to run by many Democrats. She is particularly popular among the progressive Democrats, in no small part due to her work on regulating the financial industry that contributed to the recent economic crisis. However, Warren has stated that she does not run for President in this term, though it seems the slim Democratic field could have used an extra serious contender.