dbt run_query() with a where clause based on argument

Question

I am trying to set query and call run_query() in a dbt macro called get_records but unable to set the query correctly using the argument in the where clause. Here is the macro:

{% macro get_records(lead_id) %}
    {% set sql_statement %}
        select lead_record from {{ ref('source_table') }} where lead_id = {{ lead_id }} limit 1
    {% endset %}
    {{ print(query) }}
    {% if execute %}
        {% set results = run_query(sql_statement) %}
        {% set records = results.columns[0].values() %}
    {% else %}
        {% set records = [] %}
    {% endif %}
    -- do something here
{% endmacro %}

But, the query select lead_record from {{ ref('source_table') }} where lead_id = {{ lead_id }} limit 1 getting compiled as following:

select lead_record from `source` where lead_id = lead_id

which is wrong. Is there a way to set a query using the argument value in where clause ? thanks!.