The SF Chronicle’s Susan Slusser on the A’s CF whom many have ID’d as serious trade bait.

Mark Kotsay’s future with the A’s could come into focus by the end of the week. That’s when the center fielder believes the two sides will exchange proposals on a contract extension, something he would like to get done because he wants to remain in Oakland.

But Kotsay’s agent, Greg Genske, told The Chronicle on Tuesday he is “not optimistic” about the negotiations, saying, “We’ve exchanged ideas but we haven’t made any progress.

“Mark loves playing in Oakland, he loves the organization and he wants to stay, but as of this time, it doesn’t look likely we’ll be able to get an extension done.”

Kotsay’s take was not quite as stark. “I think it’s still too early to say,” he said. “I’d be surprised if something wasn’t exchanged by the end of the week.”

If a contract extension is not completed in the next month, it is likely the team will consider moving Kotsay; the Yankees have expressed interest.

The reason the A’s might trade Kotsay: He holds a player option for next season and there is expected to be a robust market for center fielders, with New York and Boston among the possible bidders. He also has said he wants to play for a winner.

“The (time pressure) is more the A’s issue because if we don’t get something done, there’s the possibility of moving me,” Kotsay said. “But that’s more than a month away.”

GM Billy Beane, who was unavailable for comment Tuesday, has said that the team would like to reach an agreement with Kotsay. Kotsay, who is making $6.5 million this year and holds an option for the same amount next year, is believed to be looking for a two-year extension at roughly the same salary.