The Speaker of the House of Representatives is the presiding officer of the lower chamber of the Legislature. Each time a new legislature convenes every odd-numbered year the membership is constitutionally obligated to elect one of its own to occupy this position.
The Speaker is elected to the House just like all the other members, from a single-member House district that includes approximately 1/150th (recall, there are 150 members) of the Texas population. This stands in contrast to the Speaker's counterpart in the Senate, who is elected to the state-wide office of Lieutenant Governor an executive branch office.
The vote in the House to elect the Speaker occurs on the first day of the regular session. But, as many commentators have noted, the campaign for the Speaker starts many months before the actual vote. During this time, candidates for Speaker contact members of the Legislature to secure their support. This may involve a little horse-trading for, say, the chairmanship of a committee of particular interest (if you're from west Texas, you might want to chair the Agriculture and Livestock committee). More generally, legislators will want to be on the Speaker's legislative leadership team, working closely with the Speaker on the broader legislative agenda.
Of course supporting a losing candidate can be costly. Conversely, being on the winning side can be quite advantageous. The fact that the Speaker is elected every session by the membership means that the Speaker comes into the leadership position owing many more favors than the Lieutenant Governor does in the Senate. Choosing whom to support for Speaker, can be for individual legislators a bit like crossing a minefield.
The Speaker is constitutionally empowered to maintain order during debate on the floor (as opposed to debate in committee). This means recognizing legislators wishing to speak and ruling on procedural questions. The Speaker also must sign all bills and joint resolutions passed by the Legislature. All of these powers are held in addition to the powers of any regularly elected member of the House of Representatives, so the Speaker may vote on all bills, resolutions and other questions that come before the House.
The more significant powers of the Speaker are granted by the membership in the House Rules of Procedure. These are adopted by a vote of the full House at the beginning of every regular session of the Legislature. These rules empower the Speaker to appoint the membership of all standing committees (while respecting the rule of seniority), including designating the chair and vice-chair of these committees.
In addition, the Rules of Procedure give the Speaker responsibility for referring all proposed legislation to committee, subject to the committee jurisdictions set forth in the rules. As in the Senate, internal rules give the various committees jurisdiction over legislative areas, but the Speaker enjoys considerable discretion in referring bills to the committee of his choice. This magnifies the Speaker's power over the flow of legislation. Even though the Speaker has made all committee appointments, he (historically the position has been occupied by a male) still has the power to direct legislation to the committee that will most likely produce the outcome he wants.
The rules also allow the Speaker to appoint conference committees, to create select committees, and to direct committees to conduct interim studies when the Legislature is not in session.
Finally, the Speaker of the House serves on the Legislative Council and the Legislative Audit Committee, and serves as vice-chair on the Legislative Budget Board. He is also a member of the Legislative Redistricting Board.