A socket connector (100) includes an insulative housing (1), a plurality of contacts received in the insulative housing, a cover (2) attached to the upper side of the insulative housing and a cam (3). The insulative housing defines an upper side and a lower side. The insulative housing has a first aperture (13) which extends through the upper and lower sides. The cover defines an upper surface and a lower surface and has a second aperture (23) extending through the upper and lower surfaces. The second aperture aligns with the first aperture in a vertical direction. The cam has a first cam portion (31) and a second cam portion (32) separately pre-formed and jointly combined and correspondingly received in the first and second apertures. The second cam portion is operable to urge the insulative cover relative to the insulative housing along a front-to-rear direction.