TACOMA — State Democrats will convene for their state convention this weekend to finish electing delegates to the national convention and to pass a party platform. The convention begins Friday, with delegate meetings and an evening keynote speech by Secretary of Labor Tom Perez. On Saturday, the party will adopt its platform and elect the presidential electors who will cast the state’s Electoral College vote in December. On Sunday, the remaining 34 national delegates and eight alternates to the Democratic National Convention will be elected.