(CNN) -- With all sides vowing politicking isn't in order, Republican presidential nominee Mitt Romney got a close-up view Friday of the devastation caused this week by Hurricane Isaac -- days ahead of a visit by his November foe, President Barack Obama.
Romney went to Louisiana's Jefferson Parish, glimpsing the flooding and downed trees along with Gov. Bobby Jindal and Sen. David Vitter, both fellow Republicans.
The former Massachusetts governor, accompanied by his wife, Ann, said the trip was "to learn and obviously to draw some attention to what's going (on) here... so that people around the country know that people down here need help."
Hours earlier, the White House announced that Obama canceled a trip to Cleveland and would instead head Monday to Louisiana.
Obama will meet officials dealing with Isaac's impact and "making sure that unmet needs are being met and that the federal response led by FEMA is helping citizens in the affected areas and the state and local officials who are responding to the storm," White House press secretary Jay Carney said.
The president on Friday addressed the situation to start his speech to troops in Fort Bliss, Texas. He vowed the government will "keep doing everything that it can" to help those suffering due to the storm.
"As a country, we stand united with our fellow Americans in their time of need," Obama said.
Jindal echoed that view, saying he was "thrilled" both major party's presidential nominees were making time to visit his state.
"There's no time for partisan politics in Louisiana at this point in time," Jindal said.
Mary Landrieu, the Democratic senator from Louisiana, made a political point directed at Romney during a news conference in Plaquemines Parish. She said she hopes the Republican nominee will realize the importance of the Army Corps of Engineers and its projects that tackle hurricanes and storm damage. She called the agency's budget "underfunded."
"Two billion dollars is not nearly enough new investment in core infrastructure for our nation, so one of the things I hope (Romney) sees firsthand when he's here is that," she said. "I realize he's all about cutting the federal budget, but this is one agency that absolutely cannot take any additional cuts," she said.
Isaac made landfall on the seventh anniversary of Hurricane Katrina, which overwhelmed levees and contributed to nearly 1,800 deaths.
After slamming into the United States as a Category 1 hurricane on Tuesday, Isaac weakened considerably but still dumped ample rain as it headed north through Arkansas and toward Missouri.
"There are some individuals in the metropolitan area of New Orleans that have suffered damages in excess of what they suffered during Katrina," said Mayor Mitch Landrieu, where 20 inches of rain fell, according to the National Weather Service.
With 25 mph sustained winds, the tropical depression moved Friday night into the Middle Mississippi River Valley, where it is expected to dump several more inches of rain, the National Weather Service said.
By Saturday night, it should start affecting the Ohio River Valley.
Already, Isaac caused at least 19 deaths in Haiti while churning north from the Caribbean and into the Gulf of Mexico and then another four in Louisiana and Mississippi. It has also left its share of destruction and headaches, many of which persisted on Friday.
That includes hundreds of thousands without power around the Gulf Coast, including 430,000 Entergy Louisiana customers Friday evening.
Such such storm-related problems led the Louisiana Department of Agriculture and Forestry to offer up to 50 gallons of fuel per day for purchase by dairy farmers who were without power. The same department noted more than 160,000 gallons of diesel and 138,000 gallons of unleaded fuel had been requested by hospitals, law enforcement agencies and other emergency operators.
Floodwaters remained high, meanwhile, in numerous parishes where the lingering heavy rain combined with storm surges to inundate scores homes and businesses.
In Plaquemines Parish, for instance, officials intentionally breached a levee to help drain floodwater in nearby communities.
The bodies of a man and woman were found in 7 feet of water in the kitchen of a home in the parish, officials said late Thursday. An autopsy will determine the cause of the death for the couple, Nungesser said.
In St. Tammany Parish, a Slidell resident was killed while driving through four feet of floodwater, state police said.
Ascension Parish announced voluntary evacuations for parts of the region.
Animals have also been impacted -- from the 94 cats and dogs in shelters in Alexandria and another 63 in Haughton, to state authorities waiving restrictions to allow beef cattle to be evacuated from Louisiana to Texas.
The storm had a "major impact" in Mississippi, Gov. Phil Bryant said. The state was among those soaked by the storm, including 17 inches in Kiln.
A falling tree killed a tow truck driver in the state as he was attempting to clear debris on a road, officials said.
Water levels at 700-acre Lake Tangipahoa dropped Friday as authorities pumped water from it, meaning a damaged earthen dam may not have to be breached, Mississippi Emergency Management spokesman Brett Carr said.
"We don't know if it's going to be enough," said Carr of the water level drops. "We are clearing land in preparation for the cut."
Residents living within a half-mile of the Tangipahoa River, which runs from the lake south into Louisiana, remain under an evacuation order.
Officials in Louisiana say two bridges in Tangipahoa Parish have been closed because the river's water level has been too high.
Amid such continued challenges and the massive clean-up, there were also signs Friday of life returning to normal.
Days after closing off the waterway, the Coast Guard captain at the New Orleans port on Friday reopened the Mississippi River, from Baton Rouge to the mouth of the river, to limited vessel traffic.
"Although the Mississippi River was heavily impacted by the storm, the navigational channel is in good condition. The Coast Guard is working with the maritime industry to respond to a number of ship groundings and barge strandings along the riverbank caused by the river surge and high winds of the storm," the Coast Guard said.
And Louis Armstrong New Orleans International Airport officials said Friday that flights had resumed and commercial power had been restored.
Terrebonne Parish in Louisiana announced, meanwhile, that its curfew had been lifted, its government offices reopened and its public transit system was back in operation -- though a boil water advisory remains in effect.
Jindal praised the selfless actions of people, like a caretaker who stayed behind to help nursing home patients despite losing homes during Isaac and Katrina.
"I'm in awe of the generosity and resilience of the people," he said.
CNN's Brian Todd and Rich Phillips contributed to this report.