Lee's issue is the dollars, which amount to about $96 million through 2015. Beckett has a few different obstancles, including the money ($38 million to go through 2014), and his reputation for moodiness.
Lee can't veto a trade to the Rangers as they are one of the teams not on his 21-team no-trade list. Beckett has blanket 10-and-5 veto but there's a belief he might approve Texas or Atlanta.
The Rangers are looking for a top starter after Colby Lewis was lost for the year. They could also move Alexi Ogando to the rotation, so they are looking at bullpen options, including Jonathan Broxton, as well.