One of the season's highest-profile proxy battles is being put to a vote on Thursday as activist investor William Ackman and Target Corp face off at the retailer's annual meeting.

In the heated proxy contest, Ackman is seeking enough shareholder votes to win five seats on the retailer's board, while Target is running a slate of four incumbent directors.

Shareholders will also have to vote on the size of the board -- Target wants to set it at 12, while Ackman claims it should be 13.

In an interview on CNBC on Thursday morning before the meeting, Ackman said many Target shareholders had not yet cast their votes, and he still did not know what the outcome of the proxy contest would be.

Ackman, whose Pershing Square Capital Management has a 7.8 percent stake in the retailer, has pushed Target to buy back its stock and sell off its credit card operations.

While Target partially complied with those requests, Ackman launched his proxy contest in March after the retailer rejected his proposal to spin off the land under its stores into a real estate investment trust to boost its stock price.

Ackman has since said that he is running the proxy contest to add executives to Target's board who have expertise in credit cards, real estate and food retailing -- areas he contends are critical to Target's ability to compete successfully in the future.

But Target maintains he is seeking the seats simply as a way to push through his risky real estate transaction.

The proxy contest is seen as an unusual one because many analysts and investors have praised Target as a best-in-class retailer with a capable management team.

Target shares are up about 15 percent this year, while those of rival discounter Wal-Mart Stores Inc are down roughly 12 percent.

But Target's shares have fallen 33 percent since April of 2007, when Ackman began accumulating his stake, while Wal-Mart shares have risen 5 percent during that time.

Target's business has faltered amid the recession as shoppers pare back purchases of its clothes and home decor, and stick to buying basics, such as food or medicine -- a trend that favored rival Wal-Mart. Target is now trying to add more food to its merchandise assortment to lure shoppers into its stores more frequently.

Some investors have acknowledged that Ackman, who is known for well-researched and often successful proxy battles, could bring a fresh perspective to Target's board and push the retailer to explore new business opportunities.

Ahead of the meeting, Ackman won the support of RiskMetrics, the leading shareholder advisory firm. It recommended Target shareholders vote to elect Ackman and former Starbucks Chief Executive Jim Donald to the board. Target disputed the RiskMetrics report, saying it contained statements that were inaccurate or misleading.

Meanwhile, proxy advisory firm Glass Lewis & Co recommended that shareholders vote for all of Target's nominees, while Proxy Governance recommended that shareholders elect two of Ackman's five dissident board nominees.

(Reporting by Nicole Maestri; Editing by Steve Orlofsky, Dave Zimmerman)