Drop-D

I think he uses a pick.

Main riff/intro (played almost the whole way through the song):
G|------------------------------------|
D|------------------------------------|
A|------------------------------------|
D|--3--3--0h6--6--0h1--1--0h1-0h3h6---|

In the pre-chorus, there is no bass. (The bit with "and lets not ever take it back" etc..)

Chorus:
same as main riff but at the end it goes:
G|------------------------------------|
D|------------------------------------|
A|------------------------------------|
D|--3--3--0h6--6--0h1--1--0h1-0h6h5---|

Bridge:
G|------------------|
D|------------------|
A|------------------|
D|-3-3-3-3-3-3-3-3--|

G|---------------------------------|
D|---------------------------------|
A|---------------------------------|
D|-6-6-6-6-6-6-6-6-8-8-8-8-8-8-8-8-| x3

G|-----------------------------------------|
D|-----------------------------------------|
A|-----------------------------------------|
D|-6-6-6-6-6-6-6-6-11-11-11-11-13-13-13-13-|