President Obama warned this afternoon that Hurricane Sandy is a "big and powerful storm" that could have "fatal consequences" and urged all those in the storm's path to heed the warnings of state and local officials.

"Please listen to what your state and local officials are saying," he said from the White House briefing room. "When they tell you to evacuate, you need to evacuate. Do not delay, don't pause, don't question the instructions that are being given, because this is a serious storm and could potentially have fatal consequences if people haven't acted."

The president, who returned to Washington from the campaign trail earlier today to monitor the storm, said he has been in contact with the governors of all of the impacted states and expressed confidence in the level of preparedness.

"The conversations that I've had with all the governors indicate that at this point there are no unmet needs," he said. "I think everybody is taking this very seriously. We've got pre-positioned all the resources that we need. But right now the key is to make sure that the public is following instructions."

Obama cautioned that the storm, which is expected to make landfall later today, will be slow-moving and will impact millions of Americans.

"The public should anticipate that there's going to be a lot of power outages, and it may take time for that power to get back on. The same is true with transportation," he said. "There are going to be a lot of backlogs. And even after the storm has cleared, it's going to take a considerable amount of time for airlines, subways, trains and so forth potentially to get back, you know, on schedule, depending on the amount of damage that has occurred."

The hurricane has thrown a wrench in the final week of campaigning as both Obama and Republican presidential nominee Mitt Romney have scaled back events in key battleground states.

"I am not worried, at this point, about the impact on the election. I'm worried about the impact on families and I'm worried about the impact on our first responders. I'm worried about the impact on our economy and on transportation." the president said. "The election will take care of itself next week. Right now our number one priority is to make sure that we are saving lives, that our search-and-rescue teams are going to be in place, that people are going to get the food, the water, the shelter that they need in case of emergency, and that we respond as quickly as possible to get the economy back on track."

All told, the Obama and Romney campaigns have cancelled or changed 29 events in response to the storm. The president scrapped an appearance at a Florida campaign event this morning and has called off his rally in Wisconsin tomorrow. Romney cancelled his evening event in Wisconsin and all events Tuesday.

"This is going to be a big storm. It's going to be a difficult storm," Obama said. "The great thing about America is when we go through tough times like this, we all pull together. We look out for our friends. We look out for our neighbors. And, you know, we set aside whatever issues we may have otherwise to make sure that we respond appropriately and with swiftness. And that's exactly what I anticipate is going to happen here."