At the White House Correspondents’ Dinner last month, President Joe Biden joked: “I came to office with an ambitious agenda, and I expected it to face stiff opposition in the Senate. I just hoped it would be from Republicans.” Even though the Democrats are technically in control of the 50-50 Senate, Biden has been unable to get the necessary votes on either of the bills that form the pillars of his agenda — specifically, “Build Back Better” and voting rights. For that to change in the next two years, Democrats need their incumbents to hold on to their seats and pick up new ones. It’s hard to s…