The Republican presidential debates have not launched or destroyed any political careers - they haven't even managed to knock the billionaire real estate mogul Donald Trump out of first place, though the aggressive and polarizing tone used by the 15 remaining candidates has intensified. The five Democratic candidates, however, have been treating each other more civilly and avoiding direct confrontation - but that can still change.

Ahead of Tuesday's first Democratic debate, Hillary Clinton (pictured above) is still the most popular candidate, according to a CBS poll. With 70 percent support at the beginning of the year, she seemed to have an unbeatable edge. Now, however, a CBS poll puts her support at 46 percent, while Vermont Senator Bernie Sanders has 19 percent. Vice President Joe Biden, who has still not decided whether he will run, has 16 percent. If Biden were to officially declare that he will not run, then Clinton would probably have 56 percent support compared to Sanders 32 percent. All others running for the Democratic nomination are considered long shots.

According a presenter from CNN, the television station broadcasting the debate live from Las Vegas, Hillary Clinton has a "better hand to play," whereas the The New York Times sees her new poll results as "not as a strength, but rather a lack of strong alternatives." And, as time passes, it seems all the more unlikely that Biden will enter the race.

Surprise Sanders rise

Despite his successful campaign so far, few think that Bernie Sanders has a chance of winning. It came as a surprise that he so quickly maneuvered from the outsider position to become a serious competitor for Clinton. His affinity for unions, desire to raise the minimum wage, idealistic social policies and proposals to reform Wall Street have made him popular. Committees have formed nationwide to support the election campaign of the socialist from Vermont. Nevertheless, Sanders is a long way from getting a majority - either in the primary or the general election. "He knows that he has to imagine a large audience that does not know much about him," said Tad Devine, a senior adviser from the Sanders team.

On Tuesday, Clinton and Sanders will probably emphasize their differences. Sanders will probably portray his rival as a not-so-trustworthy representative of the establishment, while Clinton will present herself as the safe candidate with years of experience. This tactic may pay off, as the past weeks have shown that many Republican candidates, Donald Trump especially, have no eye for political realities. Clinton is undeniably one of the most experienced politicians in the United States and it is expected that she will try to use that to her advantage against Sanders, whose career in politics spans decades.

Although Clinton's tenure as secretary of state has been hailed as successful, she has not been as convincing in her election campaign. Moreover, the fact that she used a private email server while acting as secretary of state has made her an easy target for harsh criticism. President Obama told the news show "60 minutes" that Clinton had made a mistake but it had not endangered public security. This statement has been viewed as a somewhat weak defense of Clinton's actions.

Perhaps waning trust has driven Hillary Clinton to distance herself from her former boss during her campaign. She said she would handle the conflicts with Russia and Iran more forcefully than in the past. She also opposes the Keystone XL Pipeline and Obama's Trans-Pacific Partnership. Obama's deal may be seen as a landmark trade agreement, but Clinton is probably trying to woo the unions, who are against it. Several of her pledges have put her at the left end of her party's ideological spectrum, alongside Sanders: She has proposed tuition-free college education and an annual risk fee on the liabilities of banks.

According to The New York Times, Clinton's campaign offers more substance than the others in terms of clearly defined policies. After Tuesday's debate, we will know how much Americans appreciate them.