(Ebru News/AP) American presidential candidates continue to travel the state of Iowa where next Thursday, citizens will go to various locations to caucus and select candidates to run for president.

In the four corners of the state, in cities and rural areas, the issue of the assassination of former Pakistani prime minister Benazir Bhutto was either directly addressed by the candidates, or they were asked about the proper response from voters.

Republican field, Mike Huckabee, suggested that the United States must pay attention to its own back yard before jumping out into the international arena.

Mike Huckabee, Republican Presidential Candidate said:
"And, believe me today, in light of what happened yesterday in Pakistan, we all understand how dangerous a world we live in, how uncertain every single day is. But let's also be mindful that while the assassination of a presidential candidate in Pakistan does in fact touch us and it reminds us of the instability in that part of the world, we don't have to look that far to see instability in our own world, whether it's a shopping mall in Omaha just a few weeks ago."

Across the state, in Burlington, Senator John McCain urged voters to recognise that this is a critical moment in the future of Pakistani-US relations.

6. SOUNDBITE: (English) John McCain, Republican Presidential Candidate:
"Parties seem to form around people rather than people around parties. And so, we have to see if there's a logical successor to her who would be on the ballot and move forward with the elections. This is a very difficult time. It's not a time to threaten the Pakistanis. It's not a time to rattle our sabre. A couple of the presidential candidates said we should send the military into Waziristan. My friends, visit Waziristan before you send our young men and women to fight in that part of the world which has never been governed by anybody since Alexander the Great."

On the Democrats' side, Barak Obama told supporters the US should focus on the Pakistani-Afghani border, an area he suggests Pakistani President Pervez Musharraf is ignoring.

Former Senator John Edwards, who spoke to Musharraf shortly after the assassination, said the Pakistani leader needed to be dealt with " with extraordinary scepticism".

John Edwards, Democratic Presidential Candidate said:
"There are lots of problems with Musharraf, lots of problems. And this is a guy who needs to be dealt with extraordinary scepticism. But, he called back a couple of hours later and what I said to him was, first, you have to stay on this path to democracy, the rest of the world is watching you now. And he gave me his assurances that he would do that. I take that with a huge grain of salt."

In Story City, Senator Hillary Clinton called on US President George W. Bush to organise an independent international investigation into the death of Bhutto.

Hillary Clinton, Democratic Presidential Candidate said:
"So, as Americans, we have to hope that President Bush will make it very clear. We need an international, independent investigation of the death of Benazir Bhutto. The Pakistani government does not have the credibility to conduct that investigation. We need to end the blank cheque that has been provided by the Bush administration."

The torrid pace of campaigning across Iowa is expected to continue through the New Year's holiday.