While in Iraq, Biden will meet with political leaders and is "focused on encouraging Iraqi national unity and continued momentum in the fight against ISIL," according to a White House statement, using a different term for ISIS.

"The Vice President will also be discussing steps the international community can take to promote Iraq's economic stability and further regional cooperation," the statement continued. "He will also have an opportunity to thank US diplomatic and military personnel for their tremendous service."

The bigger danger

Biden has made several visits to Iraq to shore up the important bilateral relationship, particularly in the early years of the Obama administration, but this is his first trip since 2011.

A lot has changed since then.

In summer 2014, the terror group ISIS swept into the country, taking large swaths of land, including the city of Mosul.

The crisis led to a change in government as well, and while Prime Minister Haider al-Abadi is working to bridge sectarian divides, his government has been plagued in recent months by protests and opposition from predecessor Nuri al-Maliki, as well as Shiite cleric Muqtada al-Sadr.

It's an issue Biden is keenly aware of as he meets with political leaders.

"The more the political system in Baghdad is consumed with everybody keeping their job, or figuring out how to rearrange the government, the more difficult it is for everybody to be on the same page as it relates to the next step in the counter-ISIL campaign," said one senior administration official traveling with Biden. "The bigger danger you have to hedge against is that."

Earlier this month, Biden spoke with Abadi and President of the Iraqi Kurdistan Region Masoud Barzani, in which they agreed on the importance of the fight against ISIS.

The home-stretch

According to an official, President Barack Obama instructed his team at the end of the year that his "No.1 foreign policy priority in 2016 was putting ISIL on the path to defeat."

"And obviously you can't do that if you don't get it right in Iraq," the official said, noting that Biden has been the point person for Iraq since the beginning of Obama's first term.

"His visit is really just to reaffirm our partnership with Iraq," the official added, "and how important Iraq is to the Obama administration down the home stretch."

Biden's visit follows several major announcements in recent weeks regarding America's role in stepping up the fight against ISIS.

Last week, on a similar trip to Iraq, Defense Secretary Ash Carter announced the U.S. is sending 217 additional troops to Iraq. Obama then announced on Monday that the U.S. is sending 250 more troops -- mostly Special Operations forces -- to Syria. In both cases, U.S. personnel will support local forces by acting as trainers and advisers.

The U.S. is also providing Army Apache attack helicopters as part of the effort in Iraq and will be putting a long-range artillery system in southern Turkey to conduct more strikes against ISIS targets in neighboring Syria.

The official emphasized recent gains in the fight against ISIS, saying the group "doesn't enjoy freedom of movement like they used to."

"They're not able to amass forces like they used to," the official said. "And where we have dedicated local forces with coalition support, ISIL loses. So they're losing."

Aiming for Mosul

Retaking Mosul remains a high priority for the Iraqi government, but U.S. officials are hesitant to outline a specific timeline for such an operation.

"We all have to be realistic," the official said. "We're at the end of April. Once we get into June, July and August, it starts to get pretty hot in Iraq and things slow down."

"But we want to make as much progress before the summer heat really gets raging as possible," the official said.

Iraqi forces are focused on cutting key supply lines into Mosul, a senior military official told reporters Wednesday, but it may then take more than 25,000 troops to liberate the city, many of whom still need to be trained.

Carter hinted at a congressional hearing on Wednesday that preparations are well underway, saying the U.S. and Iraqis are focused on "collecting and positioning, before Ramadan commences, the forces for the envelopment of Mosul."

The Islamic holy month of Ramadan begins in early June.

Another senior administration official traveling with Biden added that a conversation regarding Mosul is likely.

"I would expect that some discussion of how this planning is coming together is pretty high on the agenda," the official said.