||Would cut taxes on middle-class families by abolishing the Alternative Minimum tax. Would keep Bush tax cuts, but reduce government spending. Wants to reform social security and healthcare.
||Would use targeted tax relief to help middle-class families cope with rising costs and stagnant pay. Would repeal Bush tax cuts for rich households. Wants to reform healthcare and renegotiate free trade deals.
||Voted for 2003 invasion and backed Bush troop escalation. Had said US forces should remain until Iraq is able to defend itself, but now predicts under his presidency most would have withdrawn by 2013.
||Opposed the war in Iraq from the outset and says there is "no military solution". Opposed "surge" strategy. Backs phased withdrawal of US forces - with all troops out of combat operations within 16 months of taking office.
||Would focus on trying to get a league of democracies to escalate economic sanctions against Iran. Refuses to rule out military solution if necessary to prevent a nuclear-armed Iran. No unconditional diplomacy.
||Favours "aggressive personal diplomacy". Would meet Iranian leaders without preconditions. He says they would change their behaviour if given incentives to do so. Military option not off the table.
||Argues his military background equips him to safeguard national security. A former Vietnam POW, he has sought to prevent the CIA using "cruel, inhumane or degrading treatment".
||Says Bush foreign policy has put US at more risk; would build alliances. Wants increased national security funding to be allocated to areas most at risk of attack.
||Says climate change is real and devastating. Says US should consider joining with every other nation in the world to reduce greenhouse gas emissions, if China and India join in.
||Wants an 80% cut in US greenhouse gas emissions by 2050. Wants US to lead global effort to combat climate change. Would invest $150bn over 10 years in clean energy.
||Has highlighted his record on supporting health care for military veterans. Favours tax incentives to encourage people to get personal health insurance.
||Backs universal coverage but would not make insurance compulsory, except for children. Subsidies would make cover more affordable and insurers would be unable to refuse coverage because of pre-existing conditions.
||Co-sponsor of bill which offered an amnesty to illegal immigrants as well as tougher border controls. Says undocumented workers already in the US should be put on path to citizenship.
||Wants US-Mexico border better policed and backs stricter penalties for employers who hire undocumented workers. Argues that giving illegal immigrants a path to citizenship is not an amnesty if they pay a fine.
||Wants to overturn the 1973 Supreme Court ruling that legalised abortion, Roe v Wade, but was supportive in the past. Would aid state efforts to boost adoption. Backed 2007 ruling banning late-term abortions.
||Trusts women to make their own choices on abortion "in conjunction with their doctors and their families and their clergy". Criticised Supreme Court decision to uphold ban on late-term abortion.