**Exhibit 31.1** **CERTIFICATION**     I, Mark R. Keller, certify that:     1. I have reviewed this Annual Report on    Form 10-K    of Republic Property Trust;     2. Based on my knowledge, this report does not contain any    untrue statement of a material fact or omit to state a material    fact necessary to make the statements made, in light of the    circumstances under which such statements were made, not    misleading with respect to the period covered by this report;     3. Based on my knowledge, the financial statements, and    other financial information included in this report, fairly    present in all material respects the financial condition,    results of operations and cash flows of Republic Property Trust    as of, and for, the periods presented in this report;     4. Republic Property Trust’s other certifying officer    and I are responsible for establishing and maintaining    disclosure controls and procedures (as defined in Exchange Act    Rules 13a-15(e)    and    15d-15(e))    and internal control over financial reporting (as defined in    Exchange Act    Rules 13a-15(f)    and    15d-15(f)),    for Republic Property Trust and have:     a) Designed such disclosure controls and procedures, or    caused such disclosure controls and procedures to be designed    under our supervision, to ensure that material information    relating to Republic Property Trust, including its consolidated    subsidiaries, is made known to us by others within those    entities, particularly during the period in which this report is    being prepared;     b) Designed such internal control over financial reporting,    or caused such internal control over financial reporting to be    designed under our supervision, to provide reasonable assurance    regarding the reliability of financial reporting and the    preparation of financial statements for external purposes in    accordance with generally accepted accounting principles;     c) Evaluated the effectiveness of Republic Property    Trust’s disclosure controls and procedures and presented in    this report our conclusions about the effectiveness of the    disclosure controls and procedures, as of the end of the period    covered by this report based on such evaluation; and     d) Disclosed in this report any change in Republic Property    Trust’s internal control over financial reporting that    occurred during Republic Property Trust’s most recent    fiscal quarter that has materially affected, or is reasonably    likely to materially affect, Republic Property Trust’s    internal control over financial reporting; and     5. Republic Property Trust’s other certifying officer    and I have disclosed, based on our most recent evaluation of    internal control over financial reporting, to Republic Property    Trust’s auditors and the audit committee of Republic    Property Trust’s board of directors (or persons performing    the equivalent functions):     a) All significant deficiencies and material weaknesses in    the design or operation of internal control over financial    reporting which are reasonably likely to adversely affect    Republic Property Trust’s ability to record, process,    summarize and report financial information; and     b) Any fraud, whether or not material, that involves    management or other employees who have a significant role in    Republic Property Trust’s internal control over financial    reporting.      By:     /s/ Mark R. Keller    Name: Mark R. Keller     Title:     Chief Executive Officer (Principal    Executive Officer)     Date: March 14, 2007