Republicans will need to sweep this year to hold onto their Senate majority in 2016

Political handicappers are predicting somewhere between a four- and eight-seat gain for Republicans in November, and most see a GOP Senate takeover as the likely Election Day outcome. But there’s a big difference between a six-seat pickup—which would give the GOP the narrowest of margins in the Senate—and a bigger win, with eight or more new Senate seats.

Winning more seats this year could help pad a Republican Senate majority enough that the tough 2016 map won’t force them to cede control right back to the Democrats in two years, even if they lose a few seats back to Democrats that November. Furthermore, the path to a bigger majority runs through swing states like Iowa and Colorado, which will be must-win battlegrounds in the next presidential election.

“You’ve got to make hay while the sun shines,” said GOP strategist Brad Todd, whose firm, OnMessage, works with top GOP Senate hopefuls like Tom Cotton and Cory Gardner. “This is the cycle for us to flip red states and purple states and get some margin. The next map is pretty blue.”