They were trying to get last-minute support in a race for governor that has been viewed as the first major referendum about Joe Biden's presidency.
McAuliffe was the governor between 2014 and 2018. He is trying to avoid disaster as polling has moved in Youngkin's favor in recent weeks. Republicans are optimistic about their chances of winning the commonwealth. They haven't won any statewide races since 2009 and Biden won it by 10 points last year.
Elsewhere: New Jersey Governor. Phil Murphy, a Democrat is running for reelection against Jack Ciattarelli, a Republican former State Assembly member. Many of the largest cities in the country are open for nominations for mayor's offices. A ballot question in Minneapolis could change the way police are run in the community where George Floyd's death last year sparked massive demonstrations across the country for racial equality.
However, Virginia's repercussions in Virginia -- a once Republican-leaning state that has become bluer in recent decades -- could have repercussions which could shake both the Republican and Democratic parties.
A McAuliffe victory could help Democrats feel more confident heading into the midterm elections next year, when control over Congress is at stake. However, a Youngkin defeat would allow Republicans to claim that they have seized political momentum and won't lose it in the midterms.
Recent weeks have seen Biden's approval ratings drop. And the Democratic-controlled Congress has yet to approve a major public works bill or a sweeping spending package that would dramatically increase government support for the social safety net.
McAuliffe was campaigning in Richmond, the state capital. Youngkin could help swing the race. They planned stops in Virginia Beach and Roanoke, Blue Ridge Mountain cities that voted for Biden last year.
Youngkin was also heading to Loudoun County for a night rally. Loudoun County is home to Washington suburbs, which have become the epicenter for parent activist groups that object to school curriculums including instruction on institutional racism as un-American. He has pledged to give parents more control over what is taught in his campaign, possibly foreshadowing similar arguments GOP candidates may use in their races next year.
McAuliffe's own swing set in northern Virginia is available for Monday night.
Each side followed the other, with a lot of overlaps, in an effort to get their most passionate supporters fired up for the weekend. Youngkin spent Sunday at the state's far southwest tip, a Republican stronghold.
McAuliffe was the governor who succeeded Democrat Ralph Northam in the state that does not allow its executive to serve consecutive terms. He hit suburban Richmond, northern Virginia, and both these areas were crucial in Biden's win a decade ago.
"I have done this job before. I was pro-business and pro-progressive. He said that he made the state more welcoming and created many jobs during his first term as a governor. "We don't want to go back."
Youngkin spoke at a rally held in Abingdon and predicted that Republicans would win all three statewide races, and regain control of the House of Delegates. This is where all 100 seats are listed on the ballot.
He stated, "This is an opportunity for us to make the statement that big government control will lose and liberty and freedom are going to win in Virginia."
McAuliffe brought in several high-profile supporters, including former President Barack Obama, President Joe Biden and celebrities Pharrell Williams as well as Dave Matthews and Dave Matthews. Youngkin has, however, avoided any public campaign visits by well-known party aides who would normally flock to a hot race.
This includes Donald Trump, former President of the United States, who will be holding a telerally on Monday for Youngkin. Youngkin has stated that he will not participate.
Youngkin was more open to Trump in the Republican primary. However, he has been careful as he attempts to win moderate voters.
Virginia's early voting system, which was greatly expanded in the two years of unification Democratic control over state government, has ended this weekend. The 2020 legislation eliminated the requirement to provide a limited excuse to vote absentee. Any qualified voter can cast a ballot beginning 45 days prior to the election.
Over 1.1 million of the state's 5.9 million registered voters cast their early ballots. This is a sharp decrease from the 2.8million early votes cast in the presidential election last year, but it's a significant increase over the 195,000 early votes that were cast during the previous gubernatorial cycles before reforms.
McAuliffe's campaign stated that it expects many Democrats will return to their pre-coronavirus-pandemic voting habits in 2018, preferring to vote in-person on Election Day.
Virginia voters don't register according to party affiliations so it was not immediately clear how the early vote split was. McAuliffe's campaign cited "strong" numbers in blue-leaning areas in northern Virginia as evidence that momentum was on their side.
Although Republicans generally oppose the Democrats' electoral reforms, they have encouraged their supporters early voting. Youngkin had a strong showing, however.