Hillary Clinton faces tough questions over Benghazi today. But with a new poll showing she is more popular with the public than ever, will she use this momentum for a 2016 presidential bid?

Hillary Clinton

It is going to be a gruelling day for Hillary Clinton. She is giving her long-awaited congressional testimony on the assault on the US diplomatic mission in Benghazi, Libya, in which four Americans, including Ambassador Chris Stevens, were killed.

It began with an appearance before the Senate Foreign Relations Committee and is followed by an appointment before the Foreign Affairs Committee. It comes as Mrs Clinton recovers from a month of health problems, which began with a stomach virus, and ended with her in hospital being treated for a blood clot near her brain.

An official inquiry into the Benghazi attack concluded that the State Department was completely unprepared to deal with the attack, citing "leadership and management" deficiencies, poor coordination and unclear lines of authority in Washington. However, the inquiry did not find Clinton personally at fault.

I am determined to leave the State Department and our country safer, stronger and more secure - Hillary Clinton

During her testimony, Mrs. Clinton is facing tough questioning from Republican Senators over the Obama administration's approach during the Benghazi attack. Over the last three months, the Republicans have repeatedly accused the Obama administration of ignoring signs of a deteriorating security situation in Libya.

Mrs. Clinton told Congress today that she is committed to improving security at US diplomatic missions worldwide following the Benghazi raid. She said: "Nobody is more committed to getting this right. I am determined to leave the State Department and our country safer, stronger and more secure."

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War of words

In the most heated exchange Mrs Clinton was quizzed by Republican Ron Johnson over initial claims by the administration that the attack had "sprung out" of protests. She immediately hit back, declaring, "what difference does it make?"

Senior Republican John McCain also went on the attack saying Clinton's testimony about what happened was "not satisfactory to me" and that many questions remained unanswered.

Mrs Clinton said members of Congress should not have delayed the extra assistance the US mission had asked for. "We've got to get our act together", she said.

Hillary Clinton's marathon day on Capitol Hill will most likely be her last in Congress before she steps down as secretary of state. President Barack Obama has nominated Senator John Kerry to succeed her and his confirmation hearing is scheduled for Thursday.

However, American journalist Lionel Shriver told Channel 4 News that despite the questions over Benghazi today, Mrs Clinton will not be leaving office on a low point.

"I don't think she had enough direct responsibility for Benghazi for it to be attached to her permanently", she said.

Lionel Shriver added, "the Republicans tried to make hay out of her failure to immediately brand the attack "terrorism", but the accusation always smacked of desperation. For me, I'm glad for a Secretary of State who doesn't leap to conclusions and waits to make statements until she knows what she's talking about".

Potential president?

American newspapers are in agreement that President Obama's swearing-in to a second term on Monday also marked the end of an extraordinary chapter in Hillary Clinton's life. But all the signs seem to suggest that this may not be the end of Mrs Clinton's career in politics.

A poll out today conducted by the Washington Post and ABC News shows 67 per cent of Americans expressed "favourable views" on the outgoing secretary of state. Not only does Mrs. Clinton's popularity dwarf that of congressional Republicans, it is also higher than that of Vice President Joe Biden, who is also regarded as potential presidential candidates for 2016.

But whether she will stand for president in 2016 is still unclear, despite a huge section of the Democratic establishment signalling their support, including her own husband. One of America's largest political action committees, Emily's List, is also among her supporters.

Dr Tim Stanley who writes for The Telegraph about US politics told Channel 4 News: "Today she is highly respected by both the Democrats and the Republicans alike. I really hope she will stand for president, otherwise she would be throwing away a great opportunity as well as lots of political capital. She has great momentum and it would be sad to lose that."

He also points to the "huge political transformation" Mrs. Clinton has undertaken since 2008. Four years ago, he says, she was seen as quite a divisive figure because conservative Americans associated her too closely with extreme liberal politics. Today, he says, she is seen as both personally and politically very successful.

"It was under her watch that Osama Bin Laden was killed, the action in Libya was carried out... and more emphasis was placed on women's and children's rights. She is respected across the globe and is the most well-travelled secretary of state in history", he said.

I really hope she will stand for president, otherwise she would be throwing away a great opportunity as well as lots of political capital - Dr Tim Stanley

Despite the high poll-ratings and the huge amount of Democratic and public support behind her, is Hillary Clinton's recent bout of illness perhaps a sign that she should be stepping away from politics? Dr Tim Stanley does not think so.

"She may have been very ill this month, but the Clintons never give up and they will never be out of the public eye. Both Bill and Hillary aren't happy unless they are in politics", he said.

However, Mrs. Clinton herself has repeatedly said she plans to end her career in public office once her term as secretary of state is completed. In October 2012 she said: "I have been on this high wire of national and international politics and leadership for 20 years... it has been an absolutely extraordinary personal honour and experience. But I really want to just have my own time back. I want to just be my own person. I'm looking forward to that."