Battle of addition: 155 days until GOP convention

(CNN) - Your guide to where the race stands for the Republican presidential nomination:

GOP delegate estimate (as of 3/25/2012):
– Mitt Romney: 568
– Rick Santorum: 261
– Newt Gingrich: 137
– Ron Paul: 71
Needed to clinch GOP nomination: 1,144
Access the latest here.

To see where the candidates are campaigning today, see below.

Upcoming contests:

April 3
– Wisconsin primary: 42 delegates at stake
– Maryland primary: 37 delegates at stake
– Washington, D.C., primary: 19 delegates at stake

April 24
– Connecticut primary: 28 delegates at stake
– Delaware primary: 17 delegates
– New York primary: 95 delegates at stake
– Pennsylvania primary: 72 delegates at stake
– Rhode Island primary: 19 delegates at stake