WASHINGTON - Senator Barrack Obama and rival Sen. Hillary Clinton are in fierce competition in the North Carolina and Indiana primaries Tuesday-- yet another critical day in the Democratic presidential nomination race. For front-runner Obama, an African-American, the primaries present an opportunity to wipe out doubts about him being a "flawed" candidate in the general election. It could also be an opportunity for Mrs Clinton to make the case that Democratic voter sentiment is swinging in her favour, and thereby cut into Obama's lead in pledged delegates and in the popular vote. The results of Tuesday's primaries will be important for both candidates. After all, the largest number of national convention delegates are at stake now than during the remaining primary season. There are 72 convention delegates at stake in Indiana and 115 in North Carolina. However, barring the most unexpected-- a blowout in either state, or twin victories by either Obama or Clinton -- the more likely outcome is a continued and inconclusive fight. As the two Democrats fight each other, the greatest beneficiary, many analysts say, will be Sen. John McCain of Arizona who in effect wrapped up the Republican nomination in February and now runs even with either of the two Democrats in national polls.