The Democratic and Republican presidential candidates are charging into Super Tuesday in a coast-to-coast battle for delegates across a dozen states -- but while they're looking for as many wins as possible, a few select states stand out as the crown jewels.

At the top of that list, in both primary contests, is Texas. The Lone Star State has the biggest cache -- 222 Democratic delegates and 155 for Republicans.  

And perhaps no candidate is fighting harder for that prize than Texas Republican Sen. Ted Cruz. The senator went all out on Monday, holding rallies in voter-rich Dallas, Houston and San Antonio in hopes of at least defeating national front-runner Donald Trump in Cruz's home state. 

"We are going to have a very good Super Tuesday," Cruz assured the Dallas crowd. Cruz has maintained a polling lead in the state, but knows a surprise loss there could doom his campaign.  

For Republicans, the second-biggest prize is Georgia, with 76 delegates at stake. Both Trump and Florida Sen. Marco Rubio put in face time with voters Monday in the final hours before polls open, while Cruz stayed rooted in Texas.  

On the Democratic side, too, Hillary Clinton and Bernie Sanders have focused their efforts. 

While Clinton declared Saturday night after her decisive win in the South Carolina primary that the campaign was going "national," the former secretary of state was concentrating Monday on two delegate-heavy states -- the Democratic-stronghold of Massachusetts (91 delegates) and Virginia (95 delegates).

Solid wins there and beyond on Super Tuesday could give her a nearly insurmountable delegate count toward the nomination.